C u r s - English for Engineering

The Article

1. The Definite Article → the is used:

- to refer to something which has already been mentioned: Open the door, please!

- when we talk about something or somebody considered unique: the only one, the Earth, the Moon, etc; e.g.: The English like tea.

- with plural states and countries or representing an union: The United Kingdom, The USA, The Netherlands.

- with proper nouns denoting groups of islands, mountain ranges, deserts, oceans, seas, rivers, channels, canals, straits:

The Black Sea, The Alps, The Thames, The Suez Canal, etc.- with names of hotels, shops, museums, theatres, institutions:

The Hilton, The White House, The British Museum, etc- with proper nouns denoting ships, trains, planes, newspapers and magazines: The Orient Express, The Time, The Sun, etc.- with adjectives at superlative, nouns converted from adjectives, denoting a class, numerals: the best, the poor, the rich, the second, etc.- with parts of the days and musical instruments: in the morning, to play the piano, etc.- in phrases like: by the way, at one hand, in the country, for the time being, on the whole, etc.

2. The Indefinite Article → a (before consonants), an (before vowels) – uses:

- when a noun is mentioned for the first time: I looked out of the window and I saw a big dog.

- with nouns representing a single item of a class: A driver is a person who drives a car. Give me a pen, please!

- with nouns denoting a profession, a job, a religion, a class: He is a Mexican. I am a teacher, she is an engineer.

- with little, few, so, such and what: She has a little money. He is such a bad boy!

- in expressions of ratio (price, speed, frequency) or with numbers and expressions of quantity: five pence a box, once a day, a dozen, a hundred, a lot of workmen, etc.- in phrases like: as a rule, as a matter of fact, at a distance, at a time, all of a sudden, in a loud/low voice, three times a week, it’s a pity, it’s a

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shame, to keep an eye on, have a toothache, be in a hurry, make a noise, to take an interest in, etc.

3. The O (zero) article is used:

- with abstract nouns (life, death, freedom, liberty, love, hate, knowledge, etc.), uncountable (milk, bread, butter, coffee, gold, iron, snow, cotton, wool, etc.) and plural nouns used in a general sense:

Most people fear death. Books are expensive.- with meals, sports and games:

I have breakfast at 8 o’clock. She sometimes plays handball.

- with proper nouns denoting persons, continents, countries, regions, towns, mountains, lakes and capes: Daniel, Europe, London, Mount Everest, etc. - before words like: church, prison, school, hospital, market; cook, nurse, teacher, milkman, used for their primary purpose:

I go to school. Teacher is giving us a test.- before names of languages, subjects, sciences:

I study Music. She likes Physics.- with names of days, months, seasons, holidays:

Sunday is his favourite day.- with the preposition by and means of transport:

I go by bike. He travels by plane.- to express indefiniteness, instead of some:

There is some / 0 sugar in this coffee.- in stock phrases: arm in arm, hand in hand, face to face, keep in mind, at dawn/at night, by day/by night, in place of, in order of, beyond hope, in case of, in front of, stay at home, from time to time, on sale, by means of, on foot, etc.

Exercises

1. Supply a/an, the, zero article:

(…) Computers are designed to process (…) information instead of (…) human beings.There are (…) bugs in this program.(…) Iron is (…) metal.There is (…) sugar in this jar.I can’t speak (…) French very well.(…) Switzerland is (…) very beautiful country.

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(…)English and Spanish are (…) most widely used languages in (…) world.Tom is (…) captain of (…) British team. George Bush was elected (…) President of (…) United States.(…) computer is (…) powerful tool. A (…) computer expert can solve such (…) problem.(…) engineer in Computers is very expensive.(…) fax gives to (…) person (…) opportunity to work at home.(…) scanner can grab (…) picture very fast.I’m going to buy (…) new computer (…) next month.(…) Last night, I found (…) virus in (…) program.Sam studies at (…) University. He attends (…) evening classes.Mary is at (…) hospital. He works as (…) nurse.She goes to (…) work by (…) bus every day.He goes to (…) school on (…) foot.We had (…) tea at 4 o’clock.(…) breakdown happened at (…) midnight / in (…) morning.I waited at (…) church for (…) hour.

2. Choose the correct article:

1. We visited (…) Tower of London when we last were in London.a) the; b) an; c) 0;

2. Ann needs a hot tea; she must have caught (…) flu.a) a; b) the: c) 0;

3. (…) U.S.A. has (…) best movies in the world.a) The; b) 0: c) A;

4. That picture was a bargain; I bought it for half (…) price.a) a; b) 0: c) the;

5. I have some relatives in (…) Netherlands.a) 0; b) the; c) a;

6. They elected him (…) manager of that institution.a) 0; b) the; c) a;

7. On (…) whole, they succeeded.a) a; b) the; e) 0;

8. He was standing at (…) door, not daring to come in.a) the; b) a; c) 0;

9. He suffers from (…) pain in his knee.a) the; b) 0; c) a;

10.She has (…) ten at (…) Maths.a) a; b) the; c) 0;

11.She can hardly remember (…) Paris you are talking about.a) the; b) 0; c) a;

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12.Every time I ask him about this problem, he beats about (…) bush.a) a; b) 0; c) the;

13.(…) friend in need is (…) friend indeed.a) an: b) a; c) 0;

14.He is paid by (…) day, so he can quit whenever he wants.a) a; b) the; c) 0;

15.(…) apple a day keeps the doctor away. (saying)a) The; b) A; c) An;

16.Finally she lost (…) patience and left.a) the; b) a; c) 0;

17.He worked very hard and made (…) fortune out of this.a) some; b). a; c) the;

18.Stop making such (…) fuss: you are overreacting!a) 0; b) a; c) the;

19.Turn to (…) eleventh page and read (…) text.a) a; b) 0; c) the;

20.When she came back from the shop, she realised (…) basket was empty.

a) the; b) a; c) 0;21.They took (…) nice half-hour walk on the alley.

a) the; b) a; c) 0;22.He takes (…) pride in having become a professor.

a) 0; b) the; c) a;23.I live in that beautiful house, on (…) left.

a) a; b) 0; c) the;24.Stop reading that magazine; take (…) Sun instead.

a) the; b) a; c) 0;25.In spite of his bad results, he remained (…) student of that

university.a) the; b) a; c) 0;

26.He was elected (…) president for the first time.a) 0; b) the; c) a;

27.(…) Time is a popular newspaper.a) 0; b) An; c) The;

28.I tell you what you want on (…) condition you keep it a secret.a) the: b) 0; c) a;

3. Translate into English:

1. Tatăl meu este inginer electronist. Ai putea să î1 rogi să îţi repare aparatul de fotografiat şi casetofonul.2. John este economist şi lucrează la o bancă. El este de asemenea preşedintele acestui club.

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3. Doar câţiva oameni au fost răniţi în accidentul de aseară.4. Elena şi-a rupt piciorul într-un accident de muncă şi acum este în spital.5. Vrei zahăr în cafea ? Nu, dar vreau puţină frişcă.6. Casa este construită din bambus, nu din cărămidă.7. Se consideră că sistemele expert efectuează sarcini extrem de complicate.8. Cineva a bătut la uşă. Du-te şi vezi cine poate fi!9. Proiectanţii de soft ţin pasul cu progresele tehnologice din domeniu.10. Obiectele grele trebuie puse sub masă, iar cele uşoare pe dulap.11. Germania Primului Război mondial a fost Germania copilăriei lui.12. Doamna Smith este Catolică sau Ortodoxă?

4. Make sentences with the phrases:

to be in a hurry; to have a talent for; all of a sudden; at dawn; face to face; beyond hope; in case of; keep in mind; by heart; from time to time.

5. Make sentences with the different meanings of the verb to set:

to set apart, to set a limit to, to set a scene, to set by, to set before, to set going, to set one’s name to something, to set the watch, to set the controls, to set the fashion, to set somebody a task, to set up, to set oneself to do something.

Television

Television is a telecommunication system for broadcasting and receiving moving pictures and sound over a distance. The term has come to refer to all the aspects of television from the television set to the programming and transmission.

The word is derived from mixed Latin and Greek roots, meaning "far seeing" (Greek "tele," meaning far, and Latin "visus," meaning seeing).

The origins of what would become today’s television system can be traced back as far as the discovery of the photoconductivity of the element selenium by Willoughby Smith in 1873, and the invention of a scanning disk by Paul Nipkow in 1884. All practical television systems use the fundamental idea of scanning an image to produce a time series signal representation. That representation is then transmitted to a device to reverse the scanning process. The final device, the television, relies on the human eye to integrate the result into a coherent image.

The first modern television broadcasts were made in England in 1936. Television did not become common in United States homes until the

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middle 1950s. While North American over-the-air broadcasting was originally free of direct marginal cost to the consumer and broadcasters were compensated primarily by receipt of advertising revenue, increasingly United States television consumers obtain their programming by subscription to cable television systems or direct-to-home satellite transmissions. In the United Kingdom, on the other hand, the owner of each television must pay a license fee annually which is used to support the British Broadcasting Corporation.

The elements of a simple television system are:An image source - this may be a camera for live pick-up of images or

a flying spot scanner for transmission of films.A sound source.A transmitter, which modulates one or more television signals with

both picture and sound information for transmission.A receiver (television) which recovers the picture and sound signals

from the television broadcast.A display device turns the electrical signals into visible light and

audible sound.Practical television systems include equipment for selecting different

image sources, mixing images from several sources at once, insertion of pre-recorded video signals, synchronizing signals from many sources, and direct image generation by computer for such purposes as station identification. Transmission may be over the air from land-based transmitters, over metal or optical cables, or by radio from synchronous satellites. Digital systems may be inserted anywhere in the chain to provide better image transmission quality, reduction in transmission bandwidth, special effects, or security of transmission from theft by non-subscribers.

Reading and vocabulary:

1. What is Television?2. What is the origin of the word television?3. Which is the fundamental idea that television systems use?4. Where and when were the first broadcasts made?5. Which are the elements of the television systems?6. How may the transmission be done?7. Why is television so important?

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Look up and find the meaning of the words:

telecommunicationbroadcastingtransmissionphotoconductivityscanning advertisingsatellitereceiverdisplaybandwidthsubscriberto modulate

Match the words or the expressions with their definitions:

1. adapter a. a part that electrically or physically connects a device to a computer or to another device

2. ampere (A) b. a high-temperature conditioning of magnetic material to relieve stresses introduces when the material was formed

3. analog device c. a microcircuit in which the output is a mathematical function of the input

4. anneal d. a device that is the beginning point for getting radio, TV or similar signals, for the final point for transmitting them

5. antenna e. the robot state in which automatic operations can be initiated

6. application f. to run the robot by executing a program

7. automatic mode

g. a program or group of programs that perform given task; a smaller form of an application is an applet

8. automatic robot run

h. a unit used to define the rate of flow of electricity (current) in a circuit; units are one coulomb (6,28x1018 electronics) per second

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The Number of Nouns

A. Variable Nouns form the Plural in the following way:

a) nouns generally add the inflection –s to the singular: book – books, cat – cats, toy – toys;b) - es is added to the singular nouns ending in -s, -z, -x, -ch, -sh:bus – buses, box – boxes, watch – watches, brush – brushes;c) - es is added to nouns ending in -y preceded by a consonant (y

changes in i): fly – flies; city – cities;d) - es is also added to nouns ending in -o preceded by a consonant:

hero – heroes, potato – potatoes, (but: photo – photos);e) - (e)s is added to nouns ending in –f(e) (which changes in -v): knife – knives, leaf – leaves, (but: roof – roofs, belief – beliefs, chief –

chiefs, etc.);f) some of the nouns that have irregular plural are: man – men, woman – women, foot – feet, tooth – teeth, goose – geese,

louse – lice, mouse – mice, child – children, ox – oxen, etc.h) foreign plurals are preserved with some borrowed nouns (Latin or

Greek): stimulus – stimuli, larva – larvae, stratum – strata, basis – bases, criterion – criteria, (but: cactus – cacti/cactuses, formula – formulae/formulas), etc.

i) - s is added to the last element of a compound noun: washing machine – washing machines, forget-me-not – forget-me-

nots; to the first element: passer-by – passers-by, son-in-law – sons-in-law; or both: woman driver – women drivers, etc.

B. Invariable Nouns have either the singular or the plural form.

1. Singular Invariable Nouns take the verb in the singular:

a) concrete uncountable nouns: bread, meat, milk, coffee, tea, luggage, furniture, money, etc.:

The money is on the table.b) abstract uncountable nouns: music, progress, nonsense,

information, knowledge, advice, homework, etc.: His advice is always good.c) proper nouns: John, The U.S.A., The Danube, etc.: The U.S.A. lies in North America.d) nouns which end in –s: news, measles (diseases), optics,

mathematics (subjects), cards, chess (games):Chemistry is easy. The news is very good.

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To express quantity of uncountable nouns we use: a piece of, a item of, a bar of, a slice of, a pound of: a piece of news, a bar of chocolate.

2. Plural Invariable Nouns take the verb in the plural:

a) tools, instruments, articles of dress: scissors, scales, trousers, pyjamas, etc.: His trousers are on the chair.

b) proper nouns: The Alps, The Carpathians, The Smith, etc.: The Alps are beautiful.c) „pluralia tantum”: savings, surroundings, customs, contents, wages,

stairs, cattle, infantry, people, police, family, team, crew, jury, etc.: The police are after the thief.d) substantivized adjectives: the rich, the poor, goods, the bad: The poor are suffering.We use pair for one article of dress or instrument: a pair of trousers.

We also use much for uncountable nouns and many for countable nouns: much money, many people.

Exercises:

1. Write down the nouns deriving from the following verbs:

agreeanalysebelievelosecorrespond expressformthreaten suggestrefer

correct promiseirritateintenddamagedeclareinheritdecideinsult sustain

2. Give the synonyms of the following words:

accumulationcompetitionsignalglobalsourceencodingcheapproductivity

developmentoriginalnoisesurvivalinformation technologiesstructure worship

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revolution labour

survival

3. Put the nouns in the plural:

1. I can see two (man) working in the garden. They are (man-worker).2. What do they need two (piano), two (camera) and three (violin) for?3. The (roof) of the buildings were covered with dead (leaf).4. These (photo) are worth staying on (shelf), not in the (album).5. She’s got the most beautiful (tooth), (lip), (hair) and (foot) I’ve ever seen.6. (Tomato) are tasty, but (potato) and (cucumber) are healthier.7. Have you seen these interesting (phenomenon)? It is a hurricane!8. Last night the Museum was robbed by (thief) and the (police) came to see the (fact).9. The (child) in these (family) have good (feature).10. The (housewife) are the principal (consumer) of the advertised (product).

4. Make sentences with the following nouns. Use the plural (sometimes you need some):

newspaperanswercoffeecheesematchhandkerchiefembargomonthdishpassengercliffboxbenchwatchchild


1) Exerciţiile şi problemele la matematică şi chimie nu sunt mereu uşoare.

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2) Zgomotul pe care îl fac vecinii noştri este de nesuportat.3) Divorţurile sunt la fel de comune ca şi căsătoriile în zilele noastre.4) Rezervele de petrol ale acestei ţări sun cele mai bogate din lume.5) Preţurile Cuprului şi Aurului au crescut în ultimii ani.6) Înainte de îmbarcarea în avion, pasagerii trebuie să aibă biletele şi paşapoartele controlate, iar pe bagaje ataşată o etichetă.7) Regulile de la frontieră interzic introducerea în ţară de arme, narcotice, substanţe toxice, transmiţătoare şi receptoare radio, etc.8) Care sunt argumentele pro şi contra metodelor moderne de publicitate?9) Universitatea noastră are cel mai mare număr de studenţi dintre toate instituţiile de învăţământ superior de la noi.10) Facultatea de Inginerie Electrică cuprinde cinci specializări : Automatică şi Informatică, Electronică aplicată, Electronică generală, Electromecanică şi Energetică Industrială.

6. Make sentences with the different meanings of the verb grow:

grow into, grow out of (habit), grow old, grow out of clothes, grow up, grow to like somebody, grown-up.

7. Match the two columns:

e.g. antique collectorantique professorcivil instructorcoal collectordental inspectordriving decoratorestate guidefilm minerfitness attendantflight agentimmigration editorinterior technicianlaboratory assistantrefuse officersales trainer

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social dealertax workertourist surgeonuniversity engineer

Video

Video is the technology of capturing, recording, processing, transmitting, and reconstructing moving pictures, typically using celluloid film, electronic signals, or digital media, primarily for viewing on television or computer monitors.

The term video (from the Latin for "I see") commonly refers to several storage formats for moving pictures: digital video formats, including DVD, QuickTime, and MPEG-4; and analog videotapes, including VHS and Betamax. Video can be recorded and transmitted in various physical media: in celluloid film when recorded by mechanical cameras, in PAL or NTSC electric signals when recorded by video cameras or in MPEG-4 or DV digital media when recorded by digital cameras.

Quality of video essentially depends on the capturing method and storage used. Digital television (DTV) is a relatively recent format with higher quality than earlier television formats and has become a standard for television video.

3D-video, digital video in three dimensions, premiered at the end of 20th century. Six or eight cameras with real-time depth measurement are typically used to capture 3D-video streams. The format of 3D-video is fixed in MPEG-4 Part 16 Animation Framework eXtension (AFX).

In the UK, Australia, and New Zealand, the term video is often used informally to refer to both video recorders and video cassettes; the meaning is normally clear from the context.

Frame rate, the number of still pictures per unit of time of video, ranges from six or eight frames per second (fps) for old mechanical cameras to 120 or more frames per second for new professional cameras. PAL (Europe, Asia, Australia, etc.) and SECAM (France, Russia, parts of Africa etc.) standards specify 25 fps, while NTSC (USA, Canada, Japan, etc.) specifies 29.97 fps. Film is shot at the slower frame rate of 24fps. To achieve the illusion of a moving image, the minimum frame rate is about ten frames per second.

Video can be interlaced or progressive. Interlacing was invented as a way to achieve good visual quality within the limitations of a narrow bandwidth. The horizontal scan lines of each interlaced frame are numbered consecutively and partitioned into two fields: the odd field

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consisting of the odd-numbered lines and the even field consisting of the even-numbered lines. NTSC, PAL and SECAM are interlaced formats. Abbreviated video resolution specifications often include an “I” to indicate interlacing. For example, PAL video format is often specified as 576i50, where 576 indicates the horizontal resolution, “I” indicates interlacing, and 50 indicate 50 (single-field) frames per second.


1. What is the video technology?2. What is the origin of the term video?3. What does this term refer to?4. When did 3D-videos first appear?5. What does the term video refer to in Australia, UK and New

Zealand?6. What is the frame rate?7. What does the abbreviation “I” indicate?8. Why is the video technology so important?


capturerecordprocesstransmitreconstructmoving picture celluloid filmelectronic signaldigital mediaview storageframeworkframe rateinterlacingprogressive

Make sentences using the following words:

capturingrecordingprocessingtransmittingreconstructing

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moving pictures celluloid filmelectronic signalsdigital mediaviewing storageresolutionMatch the words or the expressions with their definitions:

1. backbone a. a set of nods and their interconnecting links that form a central, high-speed network interconnecting other, typically lower-speed, networks or client nodes

2. backup b. abbreviation for “binary digit”, it is the smallest piece of computer information, either the number 0 or 1

3. back-up(of data)

c. a term used in video monitor technology to modify how much voltage is sent to the display area of the monitor or screen, making the background and foreground images lighter or darker

4. bit d. important procedure of saving data on a separate data storage device to prevent complete data loss in case of unexpected failure of main storage system

5. brightness e. a hard plastic tube, having an inside diameter several times that of a fiber, that holds one or more fibres

6. broadcast f. a transmitted frequency signal for radio, television or similar communications

7. buffer tube g. a system, device, file or facility that can be used as an alternative in case of a malfunction or loss of data

8. bugh. a problem with computer software that causes it to malfunction or crash

9. bus i. 8 bits of data, the basic measurement of the amount of data

10. byte j. a bus is a communication path between different components in a computer; a bus is typically composed of address wires, data wires and control wires. For example,

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a computer’s central processing unit (CPU) and memory are usually connected via a bus

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The Comparison of Adjectives

According to the way the Adjectives form their Comparison there are two kinds of Adjectives in English: regular and irregular.

A. Regular adjectives

Within the regular adjectives there are two subclasses: monosyllabic adjectives and plurisyllabic adjectives.

1. Monosyllabic adjectives (small, fat, tall, short, long, thin, etc., except right, real, wrong) form the Comparative with -er and the Superlative adding –est:

Positive Comparative: adj.+-er Superlative: the+adj+-est

small smaller the smallestfat fatter the fattestthin thinner the thinnestbig bigger the biggest

pretty prettier the prettiesthappy happier the happiest

dry drier the driest

In this group there are included „y” ending adjectives: busy, happy, lazy, lucky, noisy, etc. and some other adjectives: stupid, pleasant, simple, narrow, handsome, clever, common, quiet.

2. Plurisyllabic adjectives (modern, interesting, beautiful, boring, etc.) form the Comparative with more and the Superlative with the most:

Positive Comparative: more+adj.

Superlative: the most+adj

interesting more interesting the most interestingboring more boring the most boring

wonderful more wonderful the most wonderfuluseful more useful the most useful

B. Irregular Adjectives:

Positive Comparative Superlativegood better the bestbad worse the worst

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ill worse the worstlittle less the leastmuch more the mostmany more the most

far

late

near

old

furtherfartherlater latternearer

olderelder

the furthest (for space)the farthest (space and time)the latest (the most recent)

the last (the final)the nearest (for distance)

the next (for order)the oldest

the eldest (members of the same family)

C. Uses:

a. We use than in order to compare two things or persons: Lisa is older than Clara. The factory is higher than the bank.b. When we compare two equal things we use as+adj.+as: Harry is as good as Jack. Football is as interesting as tennis.

Chemistry is as hard as Physics.c. We use not as+adj.+as when we compare two things negatively:

Cathy is not as good as Mary. Technology is not as interesting as Informatics.

d. For plurisyllabic adjectives we use more than and less than to form the Comparative of Superiority and the Comparative of Inferiority:

That game is more interesting than the last one. This exercise is less useful than that one.

e. The Absolute Superlative is formed with very+ Adjective (Positive); sometimes very is replaced by: most, quite, terribly, extremely, awfully:

It is awfully cold. This institution is very old.

Exercises:

1. Give the meaning or the synonyms of the adjectives. Make sentences using the adjectives:

aliveabsolutecompactdisadvantageousillegal

hypersensitiveincapableinteractivemisleadingpermissive

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supernaturalunfairrepublicancarefuleconomical

courageoushandsomehistoricactiveaccidental

2. Give the Comparative and the Superlative of the following long adjectives:

affectionateathleticcautiouschildishcowardlydangerousdeceitfulinterestingexpensivefoolish

furioushastyhumorousmysteriouspoeticpoisonoussensibleskilfulsuspiciousvaluable

3. Give the Comparative and the Superlative of the following short and irregular adjectives:

richbraveoldpoorsickhardtightfardeeplonghighstupid

healthyluckyquietcruelbadgoodmuchlatenearfreeslysorry

4. Make adjectives from these words:

hesitateenjoyhumourchildwest

energyinterestannoyexhaustshock

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fascinateconfusedelightamusedetermine

fascinateastonishpleasescarebelieve

5. Make adjectives by completing the nationalities:

Country Nationality Country Nationality

Japan Australia AustralianPortugal Portuguese BelgiumSweden SpainTurkey Turkish KuwaitU.S.A. Canada CanadianRussia MexicoBrazil China ChineseNigeria ItalyGermany SingaporeSaudi Arabia Saudi DenmarkPakistan Pakistani GreeceThe Netherlands Switzerland SwissRomania FranceHungary EgyptIraq Finland

a) What languages do they speak in these countries?b) What currencies do they use?c) In what country do they use the following currencies?

yenrupeepesetayuanriyalliraeuro

zlotydongpesocruzeirodrachmaroublebaht

6. Make sentences using the verb call:

call by, call for something, call off, call on / upon somebody to do something, call somebody up.

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7. Using the following words, describe a person you admire.

than e.g.: My friend is more beautiful than yours.as …… asmorenot as ….. asmore thanless thanmostquiteterriblyextremelyawfully

8. Use the expressions in sentences of your own:

advert advertisementadvertisement agentadvertisement appealadvertisement contestadvertisement canvasseradvertisement columnadvertisement department advertisement directoryadvertisement expenditureadvertisement manageradvertisement officeadvertisement directoryadvertisement expenditureadvertisement ratesadvertisement schedule

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Computers

A computer is a machine for manipulating data according to a list of instructions known as a program.

Computers are extremely versatile. In fact, they are universal information-processing machines. A computer with a certain minimum threshold capability is in principle capable of performing the tasks of any other computer, from those of a personal digital assistant to a supercomputer, as long as time and memory capacity are not considerations. Therefore, the same computer designs may be adapted for tasks ranging from processing company payrolls to controlling unmanned spaceflights. Due to technological advancement, modern electronic computers are exponentially more capable than those of preceding generations.

Computers take numerous physical forms. Early electronic computers were the size of a large room, and such enormous computing facilities still exist for specialized scientific computation – supercomputers – and for the transaction processing requirements of large companies, generally called mainframes. Smaller computers for individual use, called personal computers, and their portable equivalent, the laptop computer, are ubiquitous information-processing and communication tools and are perhaps what most non-experts think of as "a computer". However, the most common form of computer in use today is the embedded computer, small computers used to control another device. Embedded computers control machines from fighter aircraft to digital cameras.

Originally, the term “computer” referred to a person who performed numerical calculations, often with the aid of a mechanical calculating device or analog computer. Examples of these early devices, the ancestors of the computer, included the abacus and the Antikythera mechanism, an ancient Greek device for calculating the movements of planets, dating from about 87 BC. The end of the Middle Ages saw a reinvigoration of European mathematics and engineering, and Wilhelm Schickard’s 1623 device was the first of a number of European engineers to construct a mechanical calculator. The abacus has been noted as being an early computer, as it was like a calculator in the past.

In 1801, Joseph Marie Jacquard made an improvement to existing loom designs that used a series of punched paper cards as a program to weave intricate patterns. The resulting Jacquard loom is not considered a true computer but it was an important step in the development of modern digital computers.

Charles Babbage was the first to conceptualize and design a fully programmable computer as early as 1820, but due to a combination of the limits of the technology of the time, limited finance, and an inability to

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resist tinkering with his design, the device was never actually constructed in his lifetime. A number of technologies that would later prove useful in computing, such as the punch card and the vacuum tube had appeared by the end of the 19th century, and large-scale automated data processing using punch cards was performed by tabulating machines designed by Hermann Hollerith.

During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated, special-purpose analog computers, which used a direct mechanical or electrical model of the problem as a basis for computation. These became increasingly rare after the development of the programmable digital computer.

A succession of steadily more powerful and flexible computing devices were constructed in the 1930s and 1940s, gradually adding the key features of modern computers, such as the use of digital electronics and more flexible programmability. Defining one point along this road as "the first digital electronic computer" is exceedingly difficult. Notable achievements include the Atanasoff-Berry Computer (1937), a special-purpose machine that used valve-driven (vacuum tube) computation, binary numbers, and regenerative memory; the secret British Colossus computer (1944), which had limited programmability but demonstrated that a device using thousands of valves could be made reliable and reprogrammed electronically; the Harvard Mark I, a large-scale electromechanical computer with limited programmability (1944); the decimal-based American ENIAC (1946) — which was the first general purpose electronic computer, but originally had an inflexible architecture that meant reprogramming it essentially required it to be rewired; and Konrad Zuse’s Z machines, with the electromechanical Z3 (1941) being the first working machine featuring automatic binary arithmetic and feasible programmability.

The team who developed ENIAC, recognizing its flaws, came up with a far more flexible and elegant design, which has become known as the Von Neumann architecture (or "stored program architecture"). This stored program architecture became the basis for virtually all modern computers. A number of projects to develop computers based on the stored program architecture commenced in the mid to late-1940s; the first of these were completed in Britain.

Valve-(tube) driven computer designs were in use throughout the 1950s, but were eventually replaced with transistor-based computers, which were smaller, faster, cheaper, and much more reliable, thus allowing them to be commercially produced, in the 1960s. By the 1970s, the adoption of integrated circuit technology had enabled computers to be produced at a low enough cost to allow individuals to own a personal computer.

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1. What is a computer?2. What does the term “computer” originally referred to?3. Give examples of early devices, the ancestors of the computer.4. What was ENIAC?5. Who was the first to conceptualize and design a fully programmable

computer?6. What replaced the transistor-based computers?7. Why are computers so important?


manipulatingversatilethreshold capabilitypayrollsunmannedmainframesubiquitousembeddedpunched to weaveintricatepatternsto conceptualizetinkeringtabulating

Match the words or expressions with their definitions:

1. CMOS (Complementary Metal Oxide Semiconductor)

a. a memory chip witch keeps a data record of the components installed in a computer. The CMOS uses the power of a small battery and retains data even when computer is turned off. CMOS is used by a computer to store PC’s configuration settings, such as date, time, boot sequence, drive(s) parameters etc.

2. conductivity b. a collection of similar information stored in a file, such a database or addresses, with a given structure for accepting, sorting and providing, on demand, data for

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multiple users

3. conductors c. any piece of control hardware such as an emergency-stop button, selector switch, control pendant, relay, solenoid value, sensor etc

4. conductor d. the computing term for information

5. data e. materials that allow electrical charges to flow through them

6. database f. a measure of the ease with which electrical carriers flow in a material: the reciprocal of resistivity

7. decibel g. a software module that hides the details of a particular peripheral and provides a high-level programming interface to it

8. decimal h. refers to a base ten number system using the characters 0 through 9 to represent values

9. device i. anything that allows the passage of electrons; a material or object through which electricity can flow with little resistance

10. device driver j. information indicating the nature or location of a malfunction

11. diagnostic k. a standard logarithmic unit for the ratio of two powers, voltage or currents; in fiber optics the ratio is power

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The Simple Present

Form:

Positive: S (I, you, we, they) + verb: We read every day.S (she, he, it) + verb - get -s, -es at the end:

She sleeps in the morning. He watches TV every night.

Spelling: -verbs ending in: -ss, -sh, -ch, -x, -o, get –es at the end:

He brushes his teeth.- verbs ending in consonant + y get –ies at the end:

I study French, she studies English.- verbs ending in a vowel get -s at the end:

I buy a hammer; he buys a screwdriver and a spade.

Negative:S (I, you, we, they) + don’t + verb: You don’t read every day.S (she, he, it) + doesn’t + verb: She doesn’t sleep in the morning.

Interrogative:Do + S (I, you, we, they) + verb? : Do we read every day?Does + S (she, he, it) + verb?: Does she sleep in the morning?

Use: - with adverbials: every day, every month, every year, etc.

always, ever, never, sometimes, usually, seldom, rarely, often, generally, etc.

in the morning, in the evening, at night, at noon, etc.

- to express general truths: Ice melts in the Sun. Water freezes at 0 0C.- for repeated / permanent actions (with adverbs of frequency): We go to school every afternoon. He works in a good company.- to express an officially planned action, a timetable (it has a future

meaning): The plane takes off at 5 o’clock. The program in the firm starts at 8o’clock.

- in temporal or conditional clauses: I’ll tell him if (when) I see him.- in exclamatory sentences beginning with: HERE, THERE: Here he

comes!- in proverbs, saying or sports commentaries:

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Make hay while the sun shines. The dogs bark, but the caravan goes on. X passes the ball to Y, who scores.

The Present Continuous

Form: Positive: S + to be (Present) + verb + -ing: He is playing now.

Negative: S + to be (Present) + not + verb + -ing: He is not playing now. I am not working in the laboratory right

now.

Interrogative: To be (Present) + S + verb + -ing?: Is he playing now? Are you reading now?

Spelling: - when a verb ends in one stressed vowel between two consonants,

we double the consonant: sit – sitting, swim – swimming, etc., but wait – waiting, open – opening, etc.

- when the infinitive ends in –e we drop the –e: write – writing, drive – driving, leave – leaving, etc, but see – seeing, lie – lying, die – dying, etc.

Use:- with adverbials: now, at the (this) moment, at present, nowadays,

today, tonight, still, just, etc.- to express an action in progress at the moment of speaking:

They are listening to music now. The girl is just writing a letter of application for a job.

- to express a temporary, particular action with limited duration: We usually go to work by bus, but today we are going by taxi.

- for repeated, annoying actions expressing criticism, fury, and sarcasm (with always): She is always chewing gum. She is always laughing during the courses.

- to express Futurity with verbs of movement (come, arrive, go, leave, etc.): He is going to London on Friday to close a deal.

- for changing and developing situations with get and grow: It’s getting dark. His working on computer is getting better and better.

State verbs are verbs which do not normally have continuous tenses; they describe a state rather than an action. These include:

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- verbs which express likes and dislikes: like, love, hate, dislike, enjoy, prefer, etc. e.g.: Catherine likes action films.- verbs of perception: believe, know, notice, remember, forget, recognise, understand, realise, seem, think, etc. e.g.: They don’t believe a word he is saying.- verbs of the senses: see, hear, feel, taste, look, smell, sound. We use can or could with these verbs to refer to what we see, hear, smell, taste, etc., at the moment of speaking. e.g. The pizza tastes delicious and hot. John is outside. I can see him from my window.- some other verbs: be, contain, fit, include, matter, need, belong, cost, owe, mean, own, appear, want, have (= possess), etc. e.g. This pen is yours. It belongs to you.

Some state verbs have continuous aspect, but there is a difference in meaning:

1) We think she is Spanish. (We believe it.) I’m thinking about my holiday. (I am considering…)

2) The soup tastes nice. (It has a nice flavour.) He is tasting the soup. (He is testing the flavour of…)

3) Tom can see an aeroplane. (He perceives it with his eyes.) I’m seeing Ann tonight. (I have a meeting.) He is seeing his dentist today. (He has an appointment.)

4) Daisy looks tired. (She appears to be…) Dan is looking at some photos. (He is studying them.)

5) The house smells of perfume. (It has that smell.) The dog is smelling its food. (It is sniffing.)

6) This tablecloth feels soft. (It has a soft texture.) Jane is feeling her daughter’s forehead. (She is touching…)

7) He is rude. (character - permanent state) He is being rude. (behaviour - temporary situation)

8) He has a sports car. (He possesses it.) He is having dinner now. (He is eating - idiom)

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Some idioms with have include: an accident / an experience / a dream, etc. difficulty / fun / trouble, etc. have a baby, have breakfast / lunch / dinner, have a shower, a party, etc. a bath / a shower / a swim / a party, etc.

breakfast / lunch / dinner, etc. a bath / a shower / a swim / a party, etc.

Exercises:

1. Complete each sentence with a Present Simple or a Present Continuous form, using the words given:

1. I always …………. you in this supermarket.meet

2. Mary often ………… to write her homework and learn her lessons.forget

3. She is a dancer, she ………….. at the Theatre.dance

4. I …….. the bus to the office today. My husband ……….. me a lift.not take, give

5. Sorry, I can’t talk. ………………… a shower.I have

6. She usually ………….. in English, but today she ……….... in French.sing

7. Where are you? I ………. at the kitchen table.

sit8. ………… you ……….. to come to my party?

go9. Who ………………………… to the match on Sunday?

you, go with10. He ………. to see me today, we …………. on a trip tomorrow.

come, go11. The court …………… his case next week.

hear12. Look out of the window! It’s sunny, but……………

it snow13. This is an exam! Why ………………?

you make noise14. Father always …..that he will mend the sink, but he never ……… it.

to say, do

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15. What time ……………………………? the sun set

16. We ………………… at the University at some courses.watch videos

17. Diana …………………………near to Silvia.not, usually, sit

18. Why ………………………… me like that?you, talk to

19. Ann …………………… to work by Taxi every day. go

20. This ………………outside the post office.tram, stop

2. Put the verbs in the brackets in the Present Simple or the Present Continuous:

1. Cathy? What the children (do)? I (think) they (play) with the ball in the backyard. You (hear) the noise? Yes, it (sound) like something (splash) in the water. Well, I (hope) they (not throw) my dog into the pool again. 2. What you (do) tonight? I (meet) Jenny for dinner. You always (date) Jenny. Why you (not go) out with Diane instead?

3. Why these people (stand) there? They (listen) to the man in the park. And what he (do)? He (makes) a speech about the Protection of the Environment.

4. Listen! Someone (knock) at the door. Yes, it is my English teacher. She always (come) at 5 o’clock. Can you wait for a while until we (finish) the lesson?

5. What you (look) for, dear? My pen. Someone always (steal) it! No, dear. You (not remember) where you (put) it. It (be) on the TV table.

6. What time the concert with Depeche Mode (begin)? I (not remember) exactly.

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Why you (not telephone) Denis? You (not want) to lose the concert, they (be) your favourites.

7. (Imagine) you (drive) a fast Ford and a beautiful girl (sit) next to you. She (wear) a red dress and her hair (stream) out in the wind. You (stop) at a cafeteria and (have) a coffee and a cold drink. And then ... somebody (steal) your car and your girl…

3. Choose one word or phrase marked A, B, C or D that best completes each of the following sentences:

1. "What’s that noise?" "I think the Smith ….. party."A. make; B. have; C. are having; D. are doing;

2. Your brother ….. me $500.A owns; B. is owing; C. owes; D. is owning;

3. This battery ….. for about ten months.A. longs; B. prolongs; C. lasts; D. extends;

8. Don’t disturb the priest. He ….. his prayers now.A. is talking; B. speaks; C. tells; D. is saying;

5. He ….. to be an intelligent and a brave man.A. sees; B. looks; C. is seeming; D appears;

2. The girl is ….. across the channel now.A. swimming; B. walking; C. crossing; D. sailing;

6. Jim ….. in the park every day after school.A. goes cycling; B. gets riding; C. drives bicycle; D. is having

a bike;9. I think I’m working quite efficiently, ….. ?

A. don’t I; B. aren’t I; C. am not I; D. not I;10. We must go now. It ….. dark.

A. is going; B. gets; C. becomes; D. is getting.

4. Put the verbs in the brackets in the Present Simple or the Present Continuous:

1. I (assure) you that the man who (stand) there (not spy) on us. You (imagine) things!2. I (have) a tooth out this afternoon and I (not want) to eat now, particularly that this food (taste) awful. 3. Jim, (turn) down that music! It (make) me mad! Jim, I (talk) to you!4. Tim (hear) that you (leave) for Chicago next month.5. he (not realize) that the team (wait) for him?6. Why Raquel (iron) her skirt?

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She (want) to look good because she (see) John off at the airport at 9 o’clock.7. What (worry) me is the money. I (not accept) the job unless they(offer) me a good salary.8. Grandmother (clean), mother (make) breakfast and the children (play) outside.9. You (recognise) anyone in this picture?Yes, the boy who (hit) the ball is my cousin John and the one who (sit) on the grass is my brother Sam.10. Nice to see you again! How (do) you? And where (live) now? I am fine. I (stay) at the inn for the time being. 11. We (think) of emigrating. My husband (not earn) enough money here and he (hope) to find a good job in America.12. I am sorry, Mrs Gram is not available at the moment; she (speak) to a customer.

5. Choose the appropriate tense:

1. I (see / am seeing) you (are feeling / feel) better.Yes, I am thank you.

2. Kate (belongs / is belonging) to a union.3. Xerox (makes / is making) a wide range of photocopiers.4. She (thinks / is thinking) of getting a transfer to another department.5. My boss (thinks / is thinking) I should take work home at the weekend.6. Society (changes / is changing) from one based on production to another based on more and more information.7. (Are you doing / Do you do) anything tomorrow evening?

Yes. I (am seeing / see) Jack at ten o’clock.8. What (are you looking / do you look) at?

I took some photos during my holidays. 9. What is that noise?

Our neighbours (have / are having) a party.10. This fabric (feel / is feeling) like wool.

I hope it is wool, I like it very much!11. I’m sorry, but I (do not understand / am not understanding) what you mean. Shall I explain it again?12. This cake (tastes / is tasting) awful.

I (think / am thinking) I forgot to put the sugar in it!


1. Wendy întotdeauna vine devreme la serviciu, dar astăzi întârzie.

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2. Tom se trezeşte în fiecare dimineaţă la ora 7.30. El deschide televizorul, priveşte ştirile şi apoi face un duş. Soţia lui face cafeaua şi apoi o beau împreună pe terasă. La ora 8. 15 ei se îmbracă şi pleacă la serviciu.

3. Din ce parte a României vii? Sunt născută în Moldova, dar acum locuiesc în Muntenia, în fosta Cetate de Scaun.

4. De câte ori am 2-3 zile libere, merg cu maşina la mare. Îmi place mare foarte mult.

5. De ce nu vii cu noi? Îmi pare tare rău, dar mâine merg la serviciu.6. De ce întrerupi oamenii când vorbesc la telefon? Scuze, nu mi-am

dat seama.7. Te întâlneşti cu Maria? Bineînţeles, o văd la concert diseară.

7. Make sentences with the different meanings of the verb keep:

keep something back, keep on, keep somebody off something, keep to something, keep somebody under, keep up, keep up with something.

How computers work

While the technologies used in computers have changed dramatically since the first electronic, general-purpose computers of the 1940s, most still use the stored program architecture. The design made the universal computer a practical reality.

The architecture describes a computer with four main sections: the arithmetic and logic unit (ALU), the control circuitry, the memory, and the input and output devices (I/O). These parts are interconnected by bundles of wires and are usually driven by a timer or clock (although other events could drive the control circuitry).

Conceptually, a computer’s memory can be viewed as a list of cells. Each cell has a numbered “address” and can store a small, fixed amount of information. This information can either be an instruction, telling the computer what to do, or data, the information which the computer is to process using the instructions that have been placed in the memory. In principle, any cell can be used to store either instructions or data.

The ALU is in many senses the heart of the computer. It is capable of performing two classes of basic operations. The first is arithmetic operations; for instance, adding or subtracting two numbers together. The set of arithmetic operations may be very limited; indeed, some designs do not directly support multiplication and division operations. The second class of ALU operations involves comparison operations: given two numbers, determining if they are equal, or if not equal which is larger.

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The I/O systems are the means by which the computer receives information from the outside world, and reports its results back to that world. On a typical personal computer, input devices include objects like the keyboard and mouse, and output devices include computer monitors, printers and the like, but as will be discussed later a huge variety of devices can be connected to a computer and serve as I/O devices.

The control system ties this all together. Its job is to read instructions and data from memory or the I/O devices, decode the instructions, providing the ALU with the correct inputs according to the instructions, “tell” the ALU what operation to perform on those inputs, and send the results back to the memory or to the I/O devices. One key component of the control system is a counter that keeps track of what the address of the current instruction is; typically, this is incremented each time an instruction is executed, unless the instruction itself indicates that the next instruction should be at some other location (allowing the computer to repeatedly execute the same instructions).

Since the 1980s the ALU and control unit (collectively called a central processing unit or CPU) have typically been located on a single integrated circuit called a microprocessor.

The functioning of such a computer is in principle quite straightforward. Typically, on each clock cycle, the computer fetches instructions and data from its memory. The instructions are executed, the results are stored, and the next instruction is fetched. This procedure repeats until a halt instruction is encountered.

The set of instructions interpreted by the control unit, and executed by the ALU, are limited in number, precisely defined, and very simple operations. Broadly, they fit into one or more of four categories:

1) moving data from one location to another;2) executing arithmetic and logical processes on data;3) testing the condition of data;4) altering the sequence of operations.Instructions, like data, are represented within the computer as binary

code — a base two system of counting. The particular instruction set that a specific computer supports is known as that computer’s machine language. Using an already-popular machine language makes it much easier to run existing software on a new machine; consequently, in markets where commercial software availability is important suppliers have converged on one or a very small number of distinct machine languages.

Larger computers, such as some minicomputers, mainframe computers, servers, differ from the model above in one significant aspect; rather than one CPU they often have a number of them. Supercomputers often have highly unusual architectures significantly different from the

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basic stored-program architecture, sometimes featuring thousands of CPUs, but such designs tend to be useful only for specialized tasks.


1) Which are the four main sections of a computer?2) What is ALU?3) What is I/O?4) How can the computer’s memory be viewed?5) Which are the input devices?6) Which are the output devices?7) What is the microprocessor?


circuitryinput deviceoutput devicesubtractingmultiplication divisionstraightforwardbroadlyalteringavailabilitymainframe

Match the words or expressions with their definitions:

1. dial-up a. a type of communication that is established by a switched-circuit connection using the telephone network

2. dielectric b. messages sent electronically between networked computers that may be across the office or around the world

3. e-mail c. the signal or signals received from a controlled machine or process to denote its response to the command signal; a signal which is transferred from the output back to the input for use in a closed-loop

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system

4. fax d. a system designed to prevent unauthorized access to or from a private network; all messages entering or leaving the intranet pass through system, which examines each message and blocks those that do not meet the specified security criteria

5. feedback e. non-conductor of electricity; the ability of a material to resist the flow of an electric current

6. firewall f. short for Facsimile, a fax is a scanned document that is sent over phone lines to a fax machine or computer with fax capabilities

7. firmware g. is called so because the entire sections of the microchip are erased at once or flashed. Flash memory cards lose power when they are disconnected (removed) from PC, yet the data stored in it is retained for indefinitely long time until it is rewritten

8. flash memory (card)

h. a flexible magnetic media with a typical capacity of 1.44 MB

9. floppy disk i. permanent set of instructions and data programmed directly into the circuitry of read-only memory for controlling the operation of the computer or disk drive.

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The Simple Past

Regular Verbs form the Affirmative adding –ed at the Infinitive for all the persons (worked, played, invited, etc.):

I worked hard yesterday at the office.Irregular Verbs have special past forms, for these you should see the

List of Irregular verbs.The Negative and the Interrogative of Regular Verbs and Irregular

verbs are formed with the auxiliary DO in the past (DID) and the short Infinitive of the verb:

Negative: S + did not / didn’t + Verb: I didn’t do my homework yesterday. He didn’t meet

me at the station.

Interrogative: Did + S + Verb? Did you eat your dinner? When did you meet

him?

Spelling:

When the verb ends in –e, only –d is added: like – liked, dance – danced, close – closed, etc.

When a verb in one syllable ends in a single consonant (exception c, w, x), preceded by a single vowel, the final consonant is doubled: drop – dropped, etc.

Verbs of more than one syllable, with the final syllable stressed and ending in vowel + consonant, double the consonant: omit – omitted, prefer – preferred, etc. But: visit – visited, listen – listened, etc.

Verbs ending in –c, add –k and then the suffix –ed: picnic – picnicked, etc.

For verbs ending in –y preceded by a vowel, the -y does not change, but if it is preceded by a consonant, it is changed into –i: play – played, stay – stayed, but try – tried, study – studied, etc.

Use:- with time expressions: when, then, yesterday, last

week/month/year, that day, the other day, once, ago, in 2003, etc.: I saw him the other day.

- for simple actions completed in the past: We met yesterday at the office.

- for past actions occurring in a sequence: He got up, washed, drank coffee and left for work.

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- to express a state or a habit in the past: We used to go to the theatre every evening. Grandma drank three cups of coffee a day.

- for actions which happened in a period of time, now finished: He worked in a bank for ten years.- in Indirect Speech to replace a Present Tense in Direct Speech: Sam said: „I work as an accountant.”Sam said (that) he worked as an accountant.- in Conditional clauses to express a Present Conditional:I would finish the paper if I had time.- after the verb wish or after as if/as though, if only, would rather

(different subjects), it’s (high) time: You wish you weren’t at the exam now.

The Past Continuous

Affirmative: S + was/were + Verb + -ing:He was having breakfast around 8:00 o’clock yesterday.

Negative: S + wasn’t/weren’t + Verb + -ing:Tom wasn’t talking on the phone, when I arrived.

Interrogative: Was/were + S + Verb + -ing?Was she living in New York?

Use:

- with time expressions: while, when, as, by the time, etc.- to express past action in progress at a certain moment or interrupted

by another action in the past: I was working at my papers when you arrived.While Tom was crossing the street yesterday he saw his

teacher.- to show that two or more past actions took place at the same time:

When mother was cooking, father was watching TV.While we were skimming the text, they were scanning the

documents.- for an annoying action in the past (with always):

They were always making jokes.- in Conditional Clauses, to express a Present Conditional in progress:

What would you do if she was joking about that?

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Exercises:

1. Change the following sentences in the Simple Past:

1. They are our job partners and live next door.2. She works at her project from 3 p. m. until midnight.3. Helen studies Philosophy and Social Sciences.4. We never go to the Company on weekends.5. Do you live in London?6. She knows I’m a good person, but she is afraid of me.7. Robbie never wakes up before 10 o’clock. ‘8. The children keep asking me silly questions.9. He never drinks coffee in the morning.10. Jamie drives better than I do.11. Mary always goes shopping on Saturdays.12. She writes speeches for the president of the company.13. Grandfather sometimes plays with the children.14. She understands what you say.

2. Put the verbs in brackets in the Simple Past:

1. This jacket (cost) $35. I (buy) it yesterday. The shop assistant (say) it (be) reduced. I (pay) it in cash. She (wrap) it for me and (put) it in a plastic bag.

2. I (hear) a strange noise last night. I (wake) up and (get) out of bed. I (walk) downstairs, I (take) a big knife from the kitchen and I (open) the front door. When I (look) outside I (see) a guy dressed in pyjamas. He (have) a big knife in his hand. When he (see) me he (start) to scream.

3. They (build) this house 70 years ago. Its first owner (die) in 1945. He (leave) a fortune to her son. He soon (spend) the money because he (be) a notorious gambler. He (sell) the house to an Irish manufacturer of ties.

3. Put each sentence in the Simple Past using the time adverbials:

1. Where have you bought your jeans (last week)?2. We’ve seen this comedy. (three months ago)3. He has broken his hand. (last winter)4. What time have you gone to sleep (last night)?5. She has never ridden a bike. (when she lived in Cambridge)6. What games have you played (when you were small)?

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7. The baby has fallen asleep. (immediately, after lunch)8. They have eaten all the food. (last night)9. Have you played any instruments (when you were in high

school)?10. I have spoken to your teacher on the phone. (yesterday)11. I have given him some advice. (when he was here)12. Jenny has taken some sleeping pills, and she hasn’t remembered

anything. (last night) .

4. Complete the missing parts of the sentences according to the example:

I ….. when the telephone rang. (T.V.)I was watching T.V. when the telephone rang.

1. Marie ….. when the stove made a flame. (dinner)2. Granny ….. while the dog was playing with its toy. (blouse)3. The nurse …… when the doctor came in. (injection)4. The children ….. when it started to rain. (football)5. Jillian ….. when she hurt her leg. (tennis)6. Phil ….. when he ran out of water. (tea)7. They ….. when they saw a deer. (mushrooms)8. The secretary ….. when the boss called her on the phone. (letters)9. Mum ….. when the war began. (Paris)10. Professor Smith …… when the students began the strike. (lecture)11. The reporter ….. when the police arrested him. (pictures)12. Nick ….. when he started to cough. (cigar)13. The gardener ….. when he found a snake in the grass. (lawn)14. The surgeon …... when the patient woke up. (operation)

5. Fill in the gaps with suitable verbs in the Simple Past or the Past Continuous:

1. Philip ….. the door without knocking and ….. in. The secretary …... on the phone, but she ….. down the receiver the moment she ….. his

face. 2. Yesterday I ….. down a street when I ….. into Brittany. She ….. her

car in high speed and suddenly she ….. an old lady.3. Sam ….. in his office on the 51st floor when the fire alarm …..He …..to the lift but it ….. out of order. Several people ….. to godownstairs but the blaze ….. them. The only way to go out ….. to the

roof. About thirty people ….. there for the rescue helicopter.

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4. Jeremy ….. more and more impatient. It …..four o’clock and he ….. to the Cinema with Wendy at 4:30, but the meeting ….. to have no end. He ….. at the cinema at 5:30. Wendy ….. for him, but she …..very upset.

5. I ….. in the garden when I ….. UFO. It ….. over the shed. It ….. like a big plate and it ….. strange noises. After a while a door ….. and several little creatures …...in my yard.

6. They …... some mountains, when a big bear ..… just in front of them and ….. to run after the group.

6. Make sentences with the verbs (use the past):

to advertise, to boost, to broadcast, to browse through, to bribe, to cover news, to hint, to issue, to release.

7. Put the verbs in brackets in the Past Simple or the Past Continuous:

1. While he (do) his gymnastics, Tom (feel) a cramp which (keep) him stuck to the floor for 10 minutes.

2. Susan (not know) when they (leave) for London.3. I’m sorry we (wake) up. What you (dream) about?4. While she (walk) in the park she (lose) her watch.5. They (laugh) when she (fall) off the bike and (not see) that she (be)

hurt.6. The students (dance) when the teacher (come) in.7. The boys (play) tennis when it (start) to rain. They (pick up) their

rackets and balls and (go) home.8. I (drive) my car home yesterday when I (see) an accident. I (get) out

of the car and (offer) to help.9. What (you, do) yesterday evening when I (call) you?10. On the stage of the theatre a boy (play) the piano. The tune he

(play) was great.

8. Make sentences with the different meanings of the verb give:

give away, give back, give in, give off, give out, give up, give over to.

9. Translate into English (use Past Simple&Continuous):

1. La aproximativ 6 dimineaţa, în timp ce Ana dormea, telefonul a început să sune.

2. Paula făcea mâncare când copiii şi soţul ei au sosit acasă.

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3. Mergeau împreună prin parc şi vorbeau despre serviciu când deodată au auzit un zgomot ciudat.

4. Tom asculta vrăjit tot ce îi spunea prietena lui şi nu şi-a dat seama că era târziu.

5. Liz ştia că trebuie să meargă devreme la slujbă a doua zi dimineaţa aşa că s-a grăbit spre dormitor.

6. Copiii nu erau atenţi la bunica lor, ei se uitau la desene animate.

Scanners

A scanner is a device that can read text or illustrations printed on paper and translate the information into a form the computer can use. A scanner works by digitizing an image - dividing it into a grid of boxes and representing each box with either a zero or a one, depending on whether the box is filled in. For colour and grey scaling, the same principle applies, but each box is then represented by up to 24 bits. The resulting matrix of bits, called a bit map, can then be stored in a file, displayed on a screen, and manipulated by programs. Optical scanners do not distinguish text from illustrations; they represent all images as bit maps. Therefore, you cannot directly edit text that has been scanned. To edit text read by an optical scanner, you need an optical character recognition (OCR) system to translate the image into ASCII characters. Most optical scanners sold today come with OCR packages.

Scanners differ from one another in the following respects: - scanning technology: most scanners use charge-coupled device

(CCD) arrays, which consist of tightly packed rows of light receptors that can detect variations in light intensity and frequency. The quality of the CCD array is probably the single most important factor affecting the quality of the scanner. Industry-strength drum scanners use a different technology that relies on a photomultiplier tube (PMT), but this type of scanner is much more expensive than the more common CCD-based scanners.

- resolution: the denser the bit map, the higher the resolution. Typically, scanners support resolutions of from 72 to 600 dpi.

- bit depth: the number of bits used to represent each pixel. The greater the bit depth, the more colours or greyscales can be represented. For example, a 24-bit colour scanner can represent 2 to the 24th power (16.7 million) colours. Note, however, that a large colour range is useless if the CCD arrays are capable of detecting only a small number of distinct colours.

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- size and shape: some scanners are small hand-held devices that you move across the paper. These hand-held scanners are often called half-page scanners because they can only scan 2 to 5 inches at a time. Hand-held scanners are adequate for small pictures and photos, but they are difficult to use if you need to scan an entire page of text or graphics.

Larger scanners include machines into which you can feed sheets of paper. These are called sheet-fed scanners. Sheet-fed scanners are excellent for loose sheets of paper, but they are unable to handle bound documents.

A second type of large scanner, called a flatbed scanner, is like a photocopy machine. It consists of a board on which you lay books, magazines, and other documents that you want to scan.

Overhead scanners (also called copy board scanners) look somewhat like overhead projectors. You place documents face-up on a scanning bed, and a small overhead tower moves across the page.


1. What is a scanner?2. What is a bit map?3. What does the abbreviation OCR refer to?4. How do Scanners differ from one another?5. What is a charge-coupled device?6. What does the abbreviation PMT refer to?7. How many types of scanners does the text refer to?


digitizingto distinguishphotomultiplier tuberesolutiongreyscaleshand-heldsheet-fedflatbed scanneroverhead scanner


1. GSM a. abbreviation for Global System for Mobile communications

46

2. hard disk b. a data error that does not go away with type (unlike the soft error) and is usually caused by defects in the physical structure of the disk

3. hard error c. a device used to transfer heat from one substance to another; can be air to air, air to liquid, or almost any combination

4. hardware d. acoustical waves with frequency content below the frequency of the human ear, typically below 20 Hz; can often be felt, or sensed as a vibration and can induce motion sickness and other disturbances, and even kill

5. heat exchanger e. is a type of light wave; people cannot see it because it is just outside the range of light which human eyes can detect

6. infra-red f. the physical elements and interfaces that constitute a component or system

7. infrasound g. storage medium that stores data in form of magnetic patterns on a rigid disk. Modern hard disks are usually made of several thin films deposited on both sides of the aluminium, glass etc.

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The Present Perfect Simple

Form:

Affirmative: S + have / has + verb (Past Participle / the 3rd form): I have already seen him. She has left the house.

Negative: S + haven’t / hasn’t + verb (Past Participle / the 3rd form): I haven’t played tennis, yet.

Interrogative: Have / has + S + verb (Past Participle / the 3rd form)? Has she already seen the film?

Use:

with time expressions: just, ever, never, already, yet (negations and questions), always, how long, so far, recently, often, several times, today, this week / month, etc., since (the beginning point of a period of time = Romanian: din, de la, de când), for (refers to a period that continues up to the present = Romanian: de atâta timp), etc: I have never been in Paris. Sue hasn’t left yet. I haven’t seen Alice

since 1990. The boys have known the truth for months. when we are not interested in the time of the action, but its result in

the present: I have visited an interesting museum. I haven’t done my job.

for recently completed actions: with just lately, recently, of late, till/up to now, so far, etc: The train just left the station. I haven’t seen you lately.

for incomplete periods of time, with today, this week/month/year, morning, etc: Last week we did four projects, but this week we have finished only

one. with how long for an action extended up to the present:

How long have you manufactured those products?

The Present Perfect Continuous

Form:

Affirmative: S + have / has + been + verb + -ing: I have been teaching for an hour.

Negative: S+ haven’t / hasn’t + been + verb + -ing: She hasn’t been travelling long.

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Interrogative: Has / Have + S + been + verb + -ing? Have you been sleeping?

Use:

with time expressions: how long, since, for: How long have you been studying German? I have been studying

German for 2 years / since 2004. to emphasize the continuity, the duration of the action in the present:

Dan has been watering the plants for half an hour. for actions expressing anger, irritation and criticism:

Who has been drinking my coffee?

Exercises:

1. Put the verbs in brackets in the Present Perfect Tense:

1. You ever (ride) a motorbike?2. How long you (know) your girlfriend?3. We (miss) the last bus and the concert just (start). 4. How much money you (spend) so far?5. You ever (eat) a snake?6. Where she (be)?7. I never (speak) to him since we separated8. It (not rain) here for two days.9. Your father (phone) yet?10. My little dog never (bite) anyone.11. Come to my office when you (finish) your lunch.12. Now that you (graduate) high school you should find a well-paid job.13. You (see) any comedies recently?14. Why you (not bring) your boyfriend with you?15. I (study) your plan and I think it is not good.

2. Rephrase the sentences in the Present Perfect Tense using the words given:

1. It’s ten years since I had a drink. I haven’t…..2. The last time they gave a concert was twelve months ago. They

haven’t…..3. None of his films is better than the last one. He hasn’t made…..4. Last time we saw her, she wasn’t married. We haven’t …..5. It’s a long time since I last saw her. I haven’t…..

49

6. Long time passed since she graduated from the University. She has…..

7. The last letter that Joe wrote to his wife was in 1991. Joe’s wife hasn’t…..

8. It’s two weeks since they separated. They have…..9. Don’t touch that button. Insert the CD first. Until you have…..10. I am dealing with the most difficult group of business people. I have

never…..

3. Use the words given to make complete sentences:

1. since / bike / have / that / when / had / new / you ?2. has / Jenny / boyfriend / married / finally / her?3. boring / film / in / life / I / never / my / such / a / have / seen 4. themselves / much / years / so / enjoyed / haven’t / the children / for5. at / the / he / last / repaired / CD player / has ? 6. none / a / horse / has / you / ever / before / of / ridden7. people / job / applied / more / than / for / this / a thousand / have8. you / typed / letters / have / long / time / for

4. Put the verbs in the brackets in the Present Perfect Simple / Continuous:

a) The old man (fish) since five in the morning, while his son (not fish) since yesterday at noon.b) Who (drink) my coffee? I (not touch) it and there isn’t any more!c) My boy (sleep) since 2 o’clock, but my girl (not sleep) since 3 o’clock.d) It (rain) since morning! It just (stop) now!e) The boy (listen) to that cassette since he (be) in his room.

5. Put the verbs you think that fit in the Present Perfect Continuous and also use for/since:

a) We ……………… for the final exam ……. 2 weeks.b) This man ……………… the paper …… he got on the bus.c) The patient …………………… twelve hours now.d) The gardener ……………… the flowers………seven o’clock.e) The chambermaid……… the beds ……ten minutes.f) The waiters ……….. the drinks…….morning.g) The girl ……… the horses……..half an hour.h) The architect …….. the plan for the interiors…..June.

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i) Mrs. Austin ……. the boys good manners and French……the 5 th

grade.j) Your son …….. study at Cambridge ……graduated high school.k) My aunt and uncle ……………… with us …… September.l) Mr. Simpson ……………… in this office …… he graduated.m) You ……………… this party …… a long time, haven’t you?

6. Make sentences with the Present Perfect Simple / Continuous and:

already, just, yet, how long, since, for, recently.

7. Make your own dialogues following the example given:

You / play tennis / yearsCan you play tennis?Yes, I suppose / think I can, but I haven’t played it for years.

1. Shy / fly a helicopter / he came back from the war2. you / ride a bike / 15 years old3. your friend / skate / seven years4. Jim / take good pictures / he bought my camera5. your husband / mend a T.V. / we moved to this house7. they / play soccer / they left America8. you / stand on your hands / years9. your father / sleep in a tent / he left Boy Scouts10. Martha / ski / moved to Brazil11. Tim / paint a landscape / his college years12. her grandmother / speak German / the last war13. his wife / make good cake / as long as I can remember14. our uncle / shoot a bear / he came back from Asia15. she / design a house / his first big enterprise was built16. you/drive a truck / I left the Auto Industry17. Mary / bake a fruit cake / ten years18. Johnny / wash the dishes / he got served19. you / dive / ages20. Tom / make a boat / twelve years

8. Make questions so that the answers should be the underlined words:

1. I have borrowed my mother’s car.2. Ann has dyed her hair red.3. We have lived in this town all our lives.

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4. They have been married for ten seven now.5. I have never flown in a balloon.6. He has bought an expensive watch for his sister.7. Someone has opened this door.8. Paula has written a short novel.9. The first act of the play has just finished.10. I have saved only $20 this week.11. He has written this book for his wife.12. I have telephoned him at least 5 times this evening.13. The children have broken the windows.14. The secretary has typed five legal papers so far.15. The race hasn’t started, yet.

9. Choose one item marked A, B, C or D to complete the following sentences:

1. The storm has ….. some of the tallest trees.A. felled; C. felt; B. fallen; D. fell;

2. Look! The sun has…..A. set; C. sat; B. sit; D. see;

3. I think the baby has…..A. awoke; C. woke; B. awaken; D. waked;

4. Fifty people have ….. the crash.A. lived; C. revived; B. survived; D. livened;

5. The lightning has ….. our shed!A. stricken; C. strike; B. stroked; D. struck;

6. The landlady has ….. me $20 for this room.A. charged; C. asked; B. cost; D. priced;

7. Twenty-five passengers of the plane have …..A. dyed; C. dead; B. death; D. died;

8. They ….. him president of the country.A. nominated; C. elected; B. selected; D. made;


1. Profesorul Thomson a scris mai mult de 15 articole de când lucrează în acest departament.

2. Te-ai hotărât, în sfârşit? Cât timp ai fost fără slujbă?3. Două nave ruseşti s-au scufundat după un atac submarin.4. Nu am cunoscut personal nici un American până acum.5. Lacul este îngheţat de când a apus soarele.6. Vântul a luat acoperişurile a două case din iulie.

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7. Ei au aruncat vechea maşină de spălat, vechiul frigider şi calculator şi au cumpărat altele noi.

8. Tony nu a condus niciodată un Mercedes de când este şofer profesionist.

9. Maria foloseşte calculatorul şi scanerul de 20 de minute.10. Bucătarul a pregătit o masă grozavă, el lucrează de 3 ore.

11. Put the verbs in brackets in the Present Perfect or the Simple Past:

1. You (hear) from Jenny lately?2. Yes. I (receive) a phone call yesterday. He (be) in Austria for six

months now.3. Professor Wells (write) more than five articles, recently.4. The sun rise since 5.20 o’clock in the morning.5. When he first (come) to this region he (not have) any money, but since

then he (become) the richest citizen in this town.6. I (not know) you (have) such a nice car.7. I always (want) to have a car. I (buy) this beauty last week.8. You (be) to America? 9. I (go) to the seaside last year.10. The skyscrapers (be) fantastic in Japan.11. You (make) your hotel reservation yet?12. I (write) to the Summer Inn Hotel 2 days ago, but they (not reply) yet.13. The maid (do) all the rooms in the hotel since breakfast.14. I (take) my first driving lesson the other day.15. They (throw) away the old TV set since last spring.16. The thief (hide) the money after the robbery.17. If I (be) you I would marry Lizzie.18. I (propose) to her last week, but she (turn) me down.19. I know you (travel) a lot, Mrs Smith. When you first (visit) Ireland?20. I just (heard) that Nick is out of work. They (fire) him three months

ago.

12. Make sentences with the different meanings of the verb turn:

turn against, turn away, turn down / up (the volume), turn on / off (the lights), turndown, turn in, turn into, turn out, turn to, turn up.

13. Make sentences with the following verbs (use Present Perfect Simple & Continuous):

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to add, to cater, to chill, to chop, to dip, to disturb, to go sight seeing, to melt, to offer facilities, to outline, to provide with, to put up at a hotel, to season, to shake, to sprinkle, to whisk, to put through.

Electronics

The field of electronics is the study and use of systems that operate by controlling the flow of electrons (or other charge carriers) in devices such as thermionic valves and semiconductors. The design and construction of electronic circuits to solve practical problems is part of the field of electronics engineering, and includes the hardware design side of computer engineering.

The study of new semiconductor devices and their technology is sometimes considered as a branch of physics. This page focuses on engineering aspects of electronics.

Electronic systems are used to perform a wide variety of tasks. The main uses of electronic circuits are the controlling, processing and distribution of information, and the conversion and distribution of electric power. Both of these uses involve the creation or detection of electromagnetic fields and electric currents. While electrical energy had been used for some time to transmit data over telegraphs and telephones, the development of electronics truly began in earnest with the advent of radio.

One way of looking at an electronic system is to divide it into the following parts:

- Inputs – Electronic or mechanical sensors (or transducers), which take signals from outside sources such as antennae or networks, (or signals which represent values of temperature, pressure, etc.) from the physical world and convert them into current/voltage or digital signals.

- Signal processing circuits – These consist of electronic components connected together to manipulate, interpret and transform the signals. Recently, complex processing has been accomplished with the use of Digital Signal Processors.

Outputs – Actuators or other devices such as transducers that transform current/voltage signals back into useful physical form.

One example is a television set. Its input is a broadcast signal received by an antenna or fed in through a cable. Signal processing circuits inside the television extract the brightness, colour and sound information from this signal. The output devices are a cathode ray tube that converts electronic signals into a visible image on a screen and magnet driven audio speakers.

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1. What is the field of electronics?2. What devices does the field of electronics use?3. Which are the main uses of electronic circuits?4. What do these uses involve?5. Divide the electronic system.6. What do electronic or mechanical sensors do?7. What do signal processing circuits do?


thermionicvalvessemiconductorsconversiontransducersto accomplishactuator


1. IP a. abbreviation for Internet Protocol

2. ISP b. the fastest way to get from one area of an Internet service to another; also used by search engines to find what one is searching for

3. keyboard c. a light source producing, through simulated emission, coherent, near monochromatic light

4. keyword d. on most computers, is the primary text input device

5. laser e. current flowing from input or output to case of an isolated converter at a specific voltage level

6. leakage f. abbreviation for Internet Service Provider

55

The Past Perfect Simple

Form:

Affirmative:S + had+ verb (Past Participle / the 3rd form):She had opened the door, before I arrived.You had seen me there until I noticed you.

Negative: S + hadn’t + verb (Past Participle / the 3rd form):They hadn’t read the advertisement until we came.

Interrogative: Had + S + verb (Past Participle / the 3rd form)?Had you seen him before I did?

Use:

- with time expressions: for, since, already, just, after, before, never, by, by the time, as soon as, etc:

He had finished his work after I came home from the office.- for a past action which happened before another past action or

before a stated past time: When father came home, Tom had done his homework.- to express a past action with results in the past: She was in a wheel-chair because she had had an accident.- with just, already, hardly / barely / scarcely…when and no

sooner…than to show that the past action has just been finished: We did not know that he had already fixed his bike.

The Past Perfect Continuous

Form:

Affirmative: S + had + been + verb + -ingThey had been speaking to each other before I entered the room.

Negative: S + hadn’t + been + verb + -ingShe hadn’t been travelling for a long time.

Interrogative: Had + S + been + verb+ -ing?

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Had she been writing until 9 o’clock?

Use:

- to express a past action going on over a period up to a certain past moment and to underline its continuity up to that past moment:

They had been working as engineers for 31 years before they retired. - for a past action with results in the past: They were exhausted because they had been working all day.

Exercises:

1. Choose the most appropriate tense:

1. Jane saw that the boy had moved / had been moving her bike.2. As soon as Jimmy had unpacked / had been unpacking, he went out

for a drink.3. She didn’t have time to clean the house because she had studied /

had been studying all morning.4. By the time Helen got to the gate, the car disappeared / had

disappeared.5. When he heard the news Hanna knew that Geo had lied / had been

lying to her.6. The teacher stopped teaching when she realised that the students

hadn’t listened / hadn’t been listening.7. When Dan was very young, he went / had been to school near his

house.8. When she arrived at school, Gabrielle realised that she forgot / had

forgotten her ballet shoes.9. Florence hoped / had hoped to find a ticket for the concert, but it

was sold out.10. When Sam come back home, he could see that nothing changed /

had changed.

2. Put each verb in brackets in the Past Perfect Simple, the Past Perfect Continuous or the Past Simple:

1. Sue …..(go) to open the door, but whoever was outside ……(go).2. I …..(try) to get into the house, but the door ……(lock).3. Nobody ….. (realise) that it ……(start) to rain until it was too late.4. When I ….. (see) Dana, I ….. (congratulate) her on getting the job.5. By the time the police ……(come), the thief …..(leave). .

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6. The doctor didn’t come until 10 o’clock and by then Mark ….. (wait) for three hours.

7. It took Paul three years to realise that his wife ….. (be) married before.

8. Jane eventually ….. (find) her suitcase, but by then the plane (leave).

9. Sam looked for something to eat, but his sister ….. (eat) all the food.

10. Nobody was sure what ….. (happen) the night before.

3. Make sentences with the different meanings of the verb get:

get about, get across, get along, get at, get away (with, from), get back ( at, to), get by, get down, get in, get into, get off, get on (with, at), get out, get over with, get together, get up.

4. Make sentences with the verbs:

to earn, to get into dept, to grant a loan, to open an account, to owe, to save money, to settle an account, to dabble in the stocks, to take stocks.

5. Make sentences using the Past Perfect Simple and Continuous with:

just, already, not yet, recently, since, for, never, ever, twice, it was the first time, as soon as, not until, when, after.


1. Până când Helen a ajuns la magazin, a uitat ce vroia să cumpere.2. Ieri dimineaţă, am plecat în grabă, dar nu am ajuns departe pentru

că ploua şi nu aveam umbrelă.3. Ana a decis să meargă la un doctor, deoarece de ceva vreme nu se

simţea bine.4. După ce a muncit din greu, doctorul a ajuns la soluţia dorită.5. Când a sosit la Madrid, Laura nu ştia spaniolă deloc, deoarece nu

studiase acea limbă.6. Nick a spus că se uita la televizor de ore întregi când soţia lui l-a

strigat la masă.7. Alice mi-a povestit că două săptămâni îşi căutase o rochie de

mireasă, şi în sfârşit a găsit-o.8. Nu ştiam că Dana îl cunoştea pe Bob înainte de a se întâlni la

petrecerea mea.

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Electronic devices and components

An electronic component is any indivisible electronic building block packaged in a discrete form with two or more connecting leads or metallic pads. Components are intended to be connected together, usually by soldering to a printed circuit board, to create an electronic circuit with a particular function (for example an amplifier, radio receiver, or oscillator). Components may be packaged singly (resistor, capacitor, transistor, diode etc.) or in more or less complex groups as integrated circuits (operational amplifier, resistor array, logic gate etc). Active components are sometimes called devices rather than components.

Most analog electronic appliances, such as radio receivers, are constructed from combinations of a few types of basic circuits. Analog circuits use a continuous range of voltage as opposed to discrete levels as in digital circuits. The number of different analogue circuits so far devised is huge, especially because a “circuit” can be defined as anything from a single component, to systems containing thousands of components.

Analog circuits are sometimes called linear circuits although many non linear effects are used in analog circuits such as mixers, modulators etc. Good examples of analog circuits are valve or transistor amplifiers, operational amplifiers and oscillators.

Some analog circuitry these days may use digital or even microprocessor techniques to improve upon the basic performance of the circuit. This type of circuits is usually called ”mixed signal”.

Sometimes it may be difficult to differentiate between analogue and digital circuits as they have elements of both linear and non linear operation. An example is the comparator that takes in a continuous range of voltage but puts out only one of two levels as in a digital circuit. Similarly, a transistor amplifier overdriven can take on the characteristics of a controlled switch having substantially only two levels of output.

Digital circuits are electric circuits based on a number of discrete voltage levels. Digital circuits are the most common mechanical representation of Boolean algebra and are the basis of all digital computers. To most engineers, the terms “digital circuit”, “digital system” and “logic” are interchangeable in the context of digital circuits. In most cases the number of different states of a node is two, represented by two voltage levels labelled “Low” and “High”. Often “Low” will be near zero volts and “High” will be at a higher level depending on the supply voltage in use.

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Computers, electronic clocks, and programmable logic controllers (used to control industrial processes) are constructed of digital circuits; Digital Signal Processors are another example.

Mixed-signal circuits refers to integrated circuits (ICs) which have both analog circuits and digital circuits combined on a single semiconductor die or on the same circuit board. Mixed-signal circuits are becoming increasingly common. Mixed circuits contain both analogue and digital components. Analog to digital converters and digital to analogue converters are the primary examples. Other examples are transmission gates and buffers.


1. What is an electronic component?2. How may the components be packaged?3. What is an analog circuit? How is it called?4. What may an analog circuitry use to improve the performance of the

circuit?5. What is a digital circuit? 6. What do “Low” and “High” mean?7. What I a mixed-signal circuit?


solderingapplianceoverdriveinterchangeabletransmission gatebufferanalog circuitdigital circuitmixed-signal circuit


1. microchip a. the brain of a robot

2. microphone b. the PC board of a computer that contains the bus lines and edge connectors to accommodate other boards in the system

3.microprocessor c. another term for a computer display screen

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4. monitor d. a pointing device that looks like a small box with a ball underneath it and a cable attaching it to the computer

5. motherboard e. a unit of measurement equal to one billionth of a meter; equal to 10-9 meter or 10-6 mm or 10-3

micrometer or 10 angstrom

6. mouse f. the application of science to develop new materials and processes by manipulating molecular and atomic particles

7. nanometer g. converts sound waves to electrical signal

8.nanotechnology h. a set of computers linked one to another for resources and data sharing

9. network i. the mode in which a network control program can direct a communication controller to perform such activities as pooling, device addressing, dialling and answering

10. network architecture

j. a compact element of a computer central processing unit, constructed as a single integrated unit and increasingly used as a control unit for robots

11. network control mode

k. the logical structure and operating principles (related to services, functions and protocols) of a computer network

61

The Future Tenses

1. The Future simple:

Form:

Affirmative:S (I, we) + shall + verb: I shall write the letter tomorrow.S (you, he, she, it, they) + will + verb: You will change, someday.

Negative:S (I, we) + shall not+ verb: We shall not arrive in time.S (you, he, she, it, they) + will + verb: They will not play tomorrow.

Interrogative:Shall + S (I, we) + verb?: Shall we buy this?Will + S (you, he, she, it, they) + verb?: Will you go?

Use:

a) in predictions about the future (usually with think, believe, be afraid, probably):

e.g. I believe she will marry a rich man.b) for decisions or offers:

e.g. I shall lend you my car if you wish.c) for actions which will happen in the future (without our choice):

e.g. Summer will be hot this year.d) for promises, requests, hopes, etc:

e.g. I shall send you a card from Greece.

2. “To be going to” Future:

Form:

Affirmative: S + be (Present) + going to + verb + -ing: I am going to write the letter tomorrow.

Negative: S + be (Present) + not + going to + verb + -ing: We are not going to travel to France.

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Interrogative: Be (Present) + S + going to + verb + -ing?: Are we going to buy this coat?

Use:

a) for plans, intentions:

e.g. I am going to buy an expensive car.

b) in predictions (in the near future):

e.g. You are going to hit that tree.

3. The Future Continuous:

Form:

Affirmative: S + shall / will + be + verb + -ing: I shall be working at these papers this time tomorrow.

Negative: S + shall / will + not +be + verb + -ing: He will not be sleeping in the afternoon.

Interrogative: Shall / Will + S + Be + verb + -ing?: Shall we be walking in the park tomorrow?

Use:

a) for actions in progress in the future:e.g. This time next week they will be driving to the seaside.

a) for actions which will happen in the future ( as a result of an arrangement) e.g. She will be seeing her boss at work today.c) asking about plans for the near future: e.g. Will you be going to the country this weekend?

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4. The Future Perfect:

Form:

Affirmative: S + shall / will + have + verb (Past Participle): I shall have been on holiday for a month next week.

Negative: S + shall not / will not + have + verb (Past Participle): We shall have not learned this poem by tomorrow.

Interrogative: Shall / Will + S + have + verb (Past Participle)? Shall we have finished this paper by Monday?

Use:

a) for actions which will be finished before a future time:e.g. We will have finished the cleaning by tomorrow.

b) for the duration up to a certain time in the future:e.g. By the end of the week, he will have been staying with us for

two months.

5. The Present Continuous:

- for arrangements in the near future:

e.g. He is flying to Spain next month, he has already made all the arrangements.

6. The Present Simple:

- for timetables and programmes:

e.g. The train leaves the station at nine o’clock tomorrow morning.

Exercises:

1. Put the verbs in brackets in the Future Simple and the Future Perfect:

1. She ….. (meet) a lot of people tomorrow.2. By the end of next week, Pam …… (finish) the project.

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3. He …… (not start) painting the living room before Sunday.4. Mary ….. (not go) to a concert next week.5. I hope I …… (buy) my own house by the time I’m thirty.6. ….. I (help) you with the dishes and cleaning?7. Mother …... (feel) better when she takes her medicine.8. Tom ….. (call) the agency to reserve two tickets.9. By next week, Brittany …… (move) in her new house.10. I hope the builders …… (finish) building the house by next month.

2. Choose the correct answer:

1. “What are you thinking about?”“This time next month, I ..B.. on the beach.”A will have sunbathed; B will be sunbathing; C am going to

sunbath;

2. “…… to the market today?”“Yes. Do you want me to get you something?”A Will you have gone; B Will you go; C Will you be going;

3. “Can you give Sam a message for me?”“Yes, I …..him at work later on today.”A will be seeing; B will have seen; C will see;

4. “Theo has gone to the cinema to see that film again.”“I know. After this time, he ….. it four times!” A will have seen; B will see; C will be seeing;

5. “Johnny has an exam tomorrow, doesn’t he?”“Yes. In fact, at this time tomorrow, he ….. at the exam.”A will sit; B will be sitting; C is going to sit;

6. “Are you typing another article?”“Yes. By the time I finish this one, I ….. four articles today!”A will type; B will have typed; C will be typing;

3. Put the verbs in brackets in the Future:

1. I can’t come shopping on Saturday morning because I ….. (work).2. Don’t phone me after midnight because I ….. (sleep) then.3. ……(you finish) your homework by ten o’clock?4. I haven’t made the preparations for the party, but I …..(finish) them by tonight.

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5. ….. (you go) to James’ party on Saturday night? 6. I can’t go if meeting is so early. I …..( not leave) by 4 o’clock.7. What ..... (you do) tonight? ….. (leave) at 7 o’clock to go to the station?8. Excuse me, what time ….. (the bus arrive)?9. You are right, it is cold in here! I ….. (close) the windows.10. ….. (take) your coat to the dry cleaner’s tomorrow.11. I ….. (finish) my project by the time the holidays are over.12. What ….. (plan) to do this summer? ….. (spend) a week at the mountains?

4. Choose the appropriate tense:

1. Pam is not free on Sunday. She will work. / is working. 2. I shall go / am going to a party tonight. Would you like to come with me?3. I think Jack will get / is getting the job. He has a lot of experience.4. I can’t meet you this evening. Ann will come / is coming to see me.5. Dan won’t leave / isn’t leaving San Diego at noon.6. Mark will fail / is going to fail his exam unless he studies.7. How many people will you invite / are you inviting at the party?8. I am having / will have a meeting tomorrow.

5. Complete the sentences with will or will not (won’t):

1. I’m sorry about what happened. It ….. happen again!2. Don’t worry about the exam. I’m sure you …..pass.3. Try on this jacket! It….. look nice on you.4. There is no need to take the umbrella. It …..rain.5. You must meet George. I think you ….. adore him.6. Can you wait for me? I ..... be long.7. I’ve got some great news! You ….. believe what’s happened.8. If you don’t drink anything, you ….. be thirsty later.


1. Cred că ei se vor întoarce curând, pleacă mâine la mare.2. Nu ştiam că Daisy va avea un copil, mi-a spus că naşte în februarie.3. Dacă nu ne grăbim nu vom ajunge la timp la serviciu.4. Noi lucrăm în acelaşi birou, îl voi vedea mâine la aceeaşi oră.5. Sper că vor termina de reparat maşina până săptămâna viitoare.6. O să dai cana jos de pe masă dacă nu eşti atent!7. Nu vom termina toate lucrările până mâine, abia vom fi făcut

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jumătate până diseară.8. Mergi cu noi la teatru mâine sau pleci la bunici?

7. Make sentences with the different meanings of the verb look:

look like, look after, look at, look ahead, look around, look back, look for, look in, look into, look on, look out for, look over, look to, look up (to).

Electromechanics

In engineering, electromechanics combines the sciences of electromagnetism of electrical engineering and mechanics. Mechatronics is the discipline of engineering that combines mechanics, electronics and information technology.

Electromechanical devices are those that combine electrical and mechanical parts. These include electric motors and mechanical devices powered by them, such as calculators and adding machines, switches, solenoids, relays, crossbar switches and stepping switches.

Early on, “repeaters” originated with telegraphy and were electromechanical devices used to regenerate telegraph signals. The telephony crossbar switch is an electromechanical device for switching telephone calls. They were first widely installed in the 1950s in both the United States and England, and from there quickly spread to the rest of the world. They replaced earlier designs like the Strowger switch in larger installations. Nikola Tesla, one of the great engineers, pioneered the field of electromechanics.

Paul Nipkow proposed and patented the first electromechanical television system in 1885. Electrical typewriters developed, up to the 1980s, as “power-assisted typewriters”. They contained a single electrical component in them, the motor.

At Bell Labs, in the 1940s, the Bell Model V computer was developed. It was an electromechanical relay-based monster with cycle times in seconds. In 1968 Garrett Systems were invited to produce a digital computer to compete with electromechanical systems then under development for the main flight control computer in the US Navy’s new F-14 Tomcat fighter.

Today, though, common items which would have used electromechanical devices for control, today use, less expensive and more effectively, a standard integrated circuit (containing a few million transistors) and write a computer program to carry out the same task through logic. Transistors have replaced almost all electromechanical

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devices, are used in most simple feedback control systems, and appear in huge numbers in everything from traffic lights to washing machines.


1. What is Electromechanics?2. What is Mechatronics?3. What are electromechanical devices?4. What are “repeaters”?5. When the telephony crossbar switch was first installed?6. How were the electrical typewriters?7. Which devices replaced the electromechanical devices?


electromechanicsmechatronicselectromagnetismswitchessolenoidsrelayscrossbar switchesstepping switchestypewriter


1. overcurrent a. any current in excess of a rated current of a drive to maintain or move to a new position at a given velocity and acceleration and deceleration rate

2. overhead b. the condition where more load is applied to the transducer that can measure; this will result in saturation

3. overload c. a hand-held computer

4. palm d. a variable that is given a constant value for a specified application and that may denote the application

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5. panel e. extra processing time required prior to the execution of a command or extra space required for non-data information such as location and timing; disk overhead occupies up to ten percent of drive capacity

6. parameter f. for computer or network security, a specific string of characters entered by a user and authenticated by the system in determining the user’s privileges – if any – to access and manipulate the data and operations of the system

7. password g. a line or a list of items waiting to be processed

8. queue h. a formatted display of information that appears on a display screen

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The Modal verbs

Modal verbs express modality of the action and have some specific features:

• They form the Interrogative by inversion: Can you ski?• And the Negative adding not after the modal: They cannot ski.• Modals have no Infinitive and Participle; they are followed by various forms of the infinitive: It must be cold.• Modals do not inflect, they do not have -s at the third person singular, there is no “ing” or “ed” forms: She can swim.

1. CAN – expresses:

- ability in the present (can be replaced by to be able to): He can read. - permission in the present and in the future (can be replaced by to be

allowed to, to be permitted to): You can’t park there.- possibility: The road can be blocked if necessary.

2. COULD – expresses:

- ability in the past (negation: could not, couldn’t): He could read when he was five.- permission in the present and in the future: Could I use your

phone? and also for the past: Last year the children could wake up late.- negative assumption for present and past: Ana couldn’t be playing the piano. She can’t play.

3. MAY – expresses:

- permission for present and future (replaced by to be allowed to, to be permitted to): You may park here.

- possibility for present and future: He may be at home.- possibility for the past: There is no light on, he may have gone to

bed.

4. MIGHT – expresses:

- permission (more uncertain than may): Might I use your phone?- possibility for present and future: They might be asleep.- possibility for the past: They might have missed the train.

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5. MUST – expresses:

- obligation or necessity for the present and future (negation must not, mustn’t; replaced by to have to, to be obliged to):

You must solve this problem.- assumption or possibility for present and past: Your coat is wet, it must be raining. They didn’t answer the

phone, they must have gone out.- advice for the future: You must go out, it’s great outside.- prohibition in the negative: You mustn’t walk on the grass.- the lack of necessity is expressed by: needn’t:You needn’t write that composition.

6. SHALL – expresses:

- advice or requests in the I person: How shall I write the name?- promise and obligation in the II and III person: He shall also sell

cars.

7. SHOULD – expresses:- moral obligation and advice (negation: should not, shouldn’t): You should write to your grandmother.- disapproval of the speaker in the present or past: She shouldn’t be spending so much money. She shouldn’t have

lied to him.- deduction or logical necessity for the present and the past: Tom should be in Paris now. Tom should have arrived in Paris

by now.

8. WILL – expresses:

- intention for the present and the future: The phone is ringing. I will answer it!

- invitation for the future (negation is will not, won’t): Will you have some coffee?

- requests: You will phone me, will you?- deduction or logical necessity in the present or in the past: Don’t ask Bob, he won’t know. Call him, he will have got home

by now.

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9. WOULD – expresses:

- intention in the past (negation would not, wouldn’t): She said she would write to him.

- invitation and request in the present: Would you open the window?

- repeated action in the past: When we worked together we would often have lunch.

- preference before rather, sooner: Bob would rather go to a football match than to a museum.

10. OUGHT TO – expresses:

- moral obligation or advice (negation is oughtn’t): You ought to be more careful.

- disapproval for a present or past action: You ought to tell/have told me there is/was no coffee in the house.

- deduction or logical necessity in the past: They ought to have arrived by now.

Exercises:

1. Underline the correct modals. Sometimes more than one answer may be possible:

1. Kimmy is five years old. She can / could read and write. When she was three, she could / can count to ten.

2. You ought to/ need to / revise / must for your test.3. You can’t / mustn’t / couldn’t park in this area.4. You must / can sign the contract. 5. Helen doesn’t need to/doesn’t have to/ shouldn’t get a taxi. I’ll

give him a lift. 6. We can / could / must go out for a meal later. 7. Can / Could / Must I open the window, please? 8. She couldn’t / mustn’t swim fast when she was young.9. She couldn’t / may not reach the top shelf, even though she tried.10.Could / Should I open the window, please?11.Ann can’t / mustn’t play the piano, but she can / should play the

violin.12.You mustn’t / can’t / may not lie in court.13.Tony was able to / can win the race yesterday.

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14.May / Might / Need I open the window, please? 15.Can / Will / May you help me with this exercise? 16.May / Might / Would I have one of those leaflets? 17.She must / can be on holiday. She can’t / mustn’t be working. 18.You can / may / need to leave your luggage here.19.She could / may / might finish her work by six o’clock.20.Shall / Can / Could I help you cross the road? 21.He ought to/should / may have told her the truth.22.Could / Would / Should you help me with these bags?


1 A letter arrives for you. You are sure it is from Pam.A. It may have been from Pam. B. It must be from Pam. C. It might be

from Pam.

2 You have toothache. Your sister gives you some advice.A. You may go to the dentist. B. You might go to the dentist. C. You

should go to the dentist.

3 You are looking for your skirt. You think it is in the bedroom.A. It can’t be in the bedroom. B. It should be in the bedroom. C. It

could be in the bedroom.

4 Your mother told you to do your chores. You tell her:A. I will do my chores. B. I have to do my chores. C. I might do my

chores.

5 You want your friend to baby-sit for you tonight.A. Would you baby-sit for me tonight? B. Shall you babysit for me

tonight? C. Must you baby-sit for me tonight?

6 You did the cleaning, but your mother didn’t expect you to.A. You mustn’t have done the cleaning. B. You may not have done the

cleaning. C. You needn’t have done the cleaning.

7 There was a documentary about Electronics on TV. You are sure James didn’t watch it.

A. James should have watched it. B. James may have watched it. C. James can’t have watched it.

8 You want to have a dog in your house, but your landlord tells you it isn’t allowed.

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A. You mustn’t keep pets in the flat. B. You needn’t keep pets in the flat. C. You cannot keep pets in the flat.

9 A lady is trying to open the gate. You offer to help her.A. Couldn’t I open the gate for you? B. May I open the gate for you? C.

Shall I open the gate for you?

10 You offer to do the washing up, but your mother says it isn’t necessary.

A. You may do the washing up. B You needn’t do the washing up. C You could do the washing up.

3. Rewrite the sentences using modal verbs:

a. It is possible that he has spent all the money.b. Perhaps Tommy is tired.c. I’m sure she isn’t studying hard. d. It is possible that they went out yesterday. e. I advise you to take a course in literature.f. It wasn’t necessary for her to give me a lift, but she did.g. It is possible that she has gone home.h. I advise you to have a nap.i. It isn’t necessary for Joanne to come here. j. You aren’t allowed to use this motorbike. k. I’m sure he is lying about his age.l. It is possible that the police are questioning him.m. You aren’t allowed to throw litter in the park.n. It wasn’t necessary for him to book two rooms, but he did.o. Let’s meet again tomorrow night.p. Let’s have a break in five minutes.q. It isn’t necessary for Mother to cook tonight.r. I advise you to call a doctor.

4. Complete these sentences with one of the following verbs (in the correct form):

carry cause be make repair send spend wake up Sometimes you need to use have:

1 The situation is serious. Something must be done, before it’s too late.2 I haven’t received the letter. It ….. to the wrong address.3 A decision will not ….. until the next meeting.4 I told the hotel receptionist that I wanted to ….. at 6.30 the next

morning.

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5 Do you think that less money should ….. on armaments?6 This road is in very bad condition. It should ….. a long time ago.7 The injured man couldn’t walk and had to ……8 It’s not certain how the fire started but it might ….. by an electrical

fault.

5. Write sentences with may or might:

1. Where are you going to your holidays? (to Italy?) I may go to Italy.2. Take an umbrella with you when you go out. It ….. rain later.3. What sort of car are you going to buy? (a Mercedes?) I …..4. Be careful of that dog. It ….. bite you.5. The footpath is very icy. You ….. slip.6. What are you doing these days? (go to the country?) I …..7. Where are you hanging that picture? I haven’t made up my mind yet. I …..8. I don’t think we should throw that contract away. We ….. it later.9. When is Tom coming to us? (on Saturday?) He …..10. What is Julia doing when she leaves school? (go to university?) She …..

6. Complete the sentences with must, mustn’t or needn’t:

1. We have got plenty of time. We …… leave yet.2. I can manage the shopping alone. You ….. come with me.3. We ….. walk all the way home. We can get a taxi. 4. Just help yourself if you’d like something to eat. You ….. ask first.5. We can keep this a secret between ourselves. We ...... tell anybody else.6. I understand the situation perfectly. You …... explain any further.7. I haven’t got much time. We ..... hurry.8. They have enough food at home so they ...... go shopping today.9. It’s plenty of time for you to make up your mind. You ….. decide now.10. This is a valuable book. You ….. look after it carefully and you …..it!

7. Choose the correct words underlined in each sentence:

1. The weather forecast says it may rain / had to rain tomorrow.2. We mustn’t / don’t have to go to school on Tuesday. It’s a holiday.3. I don’t think you must / should go out today.4. Sorry, I don’t understand. I can’t / mustn’t speak French.5. In this country, you have to / should have an identity card.6. My sister could walk / might walk before she started talking.7. Sorry I’m late. I had to go / may go to the doctor.

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8. You have worked very hard at the office. You could be / must be tired.9. Don’t wait for me. I could be / had to be very late.10.You don’t have to / shouldn’t eat so much chocolate. It’s bad for you!11.Sorry I’m late. I must / had to go to the doctor’s.12.Where did you have to / must you go yesterday?13.I’m sorry, but I’m not able to / don’t have to meet you tomorrow.14.This can’t be / mustn’t be your bag.15.Geo didn’t have to wait / hadn’t to wait long for the taxi.16.Helen mustn’t do / couldn’t do her task, because she was hungry.17.Sam dropped the three glasses, but was able to catch / might catch one!18.This bus had to go / might go to the centre. Shall I ask the driver?

8. Complete the sentences using modal verbs (and have if you need):

1. You ….. go and see the film. It’s very good.2. It’s a pity you ….. come to the party last night. 3. I ….. you last night but I didn’t have your number.4. I was in a hurry when I saw you. Otherwise I ….. talked to you.5. I’m surprised they didn’t wait for us. They ….. waited.6. You ….. hear a baby crying and you’re trying to study.7. You’re looking for a job. I wish somebody ….. give me a good job.8. Brian ….. buy some new clothes.9. I wish you ….. drive so fast.10.Jack always leaves the door open. This ….. annoy you.11.People ….. drop litter in the street.12.That was a long walk to our house! You ….. be tired.13.Do you ….. to go now?14.Pete ….. ride a bike when he was seven.15.Kate is only five, but she ….. swim very well.16.Mother ….. be in the bedroom. The light is on.17.Students ….. not leave their bicycles in the car park. It is forbidden.18.They ….. to try very hard, but they succeeded in the end.19.Everyone ….. be here by 7.30. Don’t be late!20. ….. you open the windows, please! It’s too hot!


1. Ar trebui să scrie acel articol.2. Trebuie să faci ce spun părinţii tăi.3. A putut să se înscrie la acea facultate deoarece avea numai note mari.4. Se poate să fi mers acolo unde crezi tu.5. Probabil că a şi terminat lucrarea pentru licenţă.

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6. Ar fi putut să îmi spună şi mie ce avea de gând.7. Poate să scrie de la 5 ani şi să citească de la 6.8. Va putea să meargă cu voi la mare , este în concediu.9. Ar putea să se ferească de pisici, doar ştie că are alergie.10.Va trebui să dea examenul mai devreme pentru ca pleacă în Spania.11.S-ar putea să nu realizeze ceea ce şi-a propus.12.Ar fi trebuit să încerce totuşi la Ştiinţe Economice.13.Nu era nevoie să meargă cu mine, ştiam drumul.14.Nu li s-a permis să aducă dicţionare la examen.

10. Make sentences with the different meanings of the verb put:

put aside, put away, put down, put off, put on (clothes / weight), put out a fire, put up with something / somebody.

Environment

An environment is a complex of surrounding circumstances, conditions, or influences in which a thing is situated or is developed, or in which a person or organism lives, modifying and determining its life or character.

In biology, ecology, and environmental science, an environment is the complex of physical, chemical, and biotic factors that surround and act upon an organism or ecosystem. The natural environment is such an environment that is relatively unaffected by human activity.

Environmentalism is a concern that deals with the preservation of the natural environment, especially from human pollution, and the ethics and politics associated with this.

In social science, environmentalism is the theory that the general and social environment is the primary influence on the development of a person or group. See also nature versus nurture.

Another social science concept is the Social environment, also known as milieu.

In computing, an environment is the overall system, software, or interface in which a program runs, such as a runtime environment or environment variable, or through which a user operates the system, such as an integrated development environment in which the user develops software or a desktop environment.

In art, an environment is a kind of installation, an artwork that surrounds the observer, and sometimes allows the audience to modify it or interact with it. The first environment was probably the installation of wool

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strings and playing children by Marcel Duchamp in a group exhibition around 1945.


1. What is an environment?2. What is an environment in biology, ecology, and environmental

science?3. What is an environment in computing?4. What is an environment in art?5. What is a milieu?6. What is Environmentalism?7. What is Environmentalism in social science?8. How important do you think it is to preserve the natural

environment?


deforestationlandfillwaste disposaloverfertilizationunleaded petrol / gaspackagingendangeredglobal warmingNo tippingdumping


1. Queue a. A line or a list of items waiting to be processed

2. RAM (Random Access Memory)

b. Is a section of memory that is permanent and will not be lost when the computer is turned off; the computer’s start-up instructions are stored

3. ROM (Read Only Memory)

c. The command given to execute a program or instruction

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4. Run d. Abbreviation for Random Access Memory; the working memory of the computer into which application programs can be loaded and executed

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The Passive Voice

The representation of the tenses in the Indicative Mood in the Passive Voice:

1. Present Simple

Active Voice : S + Infinitive (-s / -es, 3rd person, singular): The police ask John some questions.

Passive Voice: S + Be (present) + Past Participle (3rd form of the verb):

Some questions are asked by the police.

2. Present Continuous

Active Voice : S + Be (present) + V-ing:John is building the house.

Passive Voice: S + Be (present) + Being + 3rd form:The house is being built by John.

3. Past Simple

Active Voice : S + 2nd form of the verb:John gave the paper to Hellen.

Passive Voice: S + Be (past) + Past Participle (3rd form of the verb):The paper was given to Hellen by John.

4. Past Continuous

Active Voice: S + Be (past) + V-ing:Jane was giving money to her friends.

Passive Voice: S + Be (past) + Being + 3rd form:Money was being given to her friends by Jane.

5. Present Perfect Simple

Active Voice: S + Have/Has + 3rd form:They have chosen Ann as the new boss.

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Passive Voice: S + Have/Has + been + 3rd form:Ann has been chosen by them as the new boss.

6. Past Perfect Simple

Active Voice: S + Had + 3rd form:They said Dan had painted his house last week.

Passive Voice: S + Had + Been + 3rd form:They said Dan’s house had been painted last week.

7. Future Simple

Active Voice: S + Shall/Will + Infinitive:John will give flowers to Daisy.

Passive Voice: S + Shall/Will +Be + 3rd form:Daisy will be given flowers by John. Flowers will be given to Daisy.

8. Future in the Past

Active Voice: S + Should/Would + Infinitive:They said Kate would write the composition.

Passive Voice: S + Should/Would + Be + 3rd form:They said the composition would be written by Kate.

The Passive is used:

a) when the person who carries out the action is unknown or unimportant:e.g. My computer was stolen from my house last night. (I do not

know who stole the computer.) b) when the action is more important than the person who carries it out (used in news headlines, newspaper articles, advertisements): e.g. Ten teenagers were seriously injured in a bus accident last evening.

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Exercises:

1. Put the sentences in the Active Voice, where possible:

1. This castle was built in prehistoric times.2. It was probably constructed as a home for a prince’s family.3. Many of its paintings and its stained glass windows have been stolen

over the years.4. This castle is visited by a lot of tourists every year.5. My car is serviced twice a year. 6. My motorbike has already been serviced.7. Mercedes cars are made in Germany.8. The children are changed four times a day.9. My new jeans are ruined by the cat.10.The baby has been looked after by mother.

2. Rewrite the sentences in the Passive, where possible:

1. Jack opened the door.2. The door was opened by Jack.3. They did not come home early last night.4. Their mother takes them to the Circus every week.5. I left in a hurry yesterday morning.6. Megan asked the old man for directions.7. Sam is moving to a new house next month.8. The application letter arrived three days ago.9. Charles took these photographs with his camera.10. Someone is repairing the front door. 11. Do they teach German at this College?12. Did your neighbours see the fire?13. Susan hit her partner with a tennis racket.14. Mike has made the preparations for the party.15. The boss is going to give us a vacation.16. Theodore won’t have completed the papers by the end of the week.17. The police are questioning the teenagers.18. They will deliver my new furniture soon.19. Too many young children use computers nowadays.20. Is Claire cleaning the house?21. Grandmother will post the letters.22. Had Dan closed the windows before he left?

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3. Fill in with by or with:

1. The door was broken ...... a hammer.2. These books were written ….. my favourite author.3. The cake was decorated …… cream and fruit.4. The bear was shot ….. a gun.5. Tim was shouted at ….. her father.6. She was hit on the shoulder ….. an umbrella.7. I have often been told ….. him not to go there.8. The window was closed ….. Mark.9. That drawer was opened ….. Lisa ….. a knife.10.The boy was taken care of ….. his mother.

4. Put the verbs in brackets in the Passive :

“Do you still work at the Bank?”“Yes, I do. I ..... (employ) by Mr Thompson for two years now.“Oh. Do you still like it?”“Oh yes! I ….. (give) a raise and a promotion last month and I’m very happy.” “A raise? A promotion? What is your job now?”“I …..(make) Assistant Manager.”“And what do you do?”“Well, from time to time I ……(send) to other countries on business.”“I see. Do they pay you well?”“Well, I ….. (pay) very well and I hope I ….. (give) a pay raise soon.”“I am glad to hear that about you!”


1. Poliţia a fost informată de cineva că o crimă a fost comisă la Primărie.2. Engleza şi Franceza sunt predate studenţilor din această instituţie.3. Turiştilor li s-a spus să se grăbească pentru că va veni furtuna.4. Călătoria noastră a fost amânată din cauza grevei ceferiştilor.5. Fetei i s-a oferit o slujbă bună şi un salariu pe măsură.6. Ei s-au obişnuit cu noul oraş şi s-au declarat norocoşi de noua şansă oferită.7. Certificatul de căsătorie s-a dovedit a fi pierdut la Primărie.8. Au fost învinuiţi că nu ar respecta termenii şi prevederile legii.

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6. Make sentences with the different meanings of the verb come:

come to hand, come to mind, come true, come about, come after, come apart, come away, come between, come by, come for, come in, come of, come on, come out, come up (against, for, to, with).

Power stations

A power station or power plant is a facility for the generation of electric power. “Power plant” is also used to refer to the engine in ships, aircraft and other large vehicles. Some prefer to use the term energy centre because it more accurately describes what the plants do, which is the conversion of other forms of energy, like chemical energy, into electrical energy. However, power plant is the most common term in the U.S., while elsewhere power station and power plant are both widely used, power station prevailing in the Commonwealth and especially in Britain.

At the centre of nearly all power stations is a generator, a rotating machine that converts mechanical energy into electrical energy by creating relative motion between a magnetic field and a conductor. The energy source harnessed to turn the generator varies widely. It depends chiefly on what fuels are easily available and the types of technology that the power company has access to.

Thermal power stationsIn thermal power stations, mechanical power is produced by a heat

engine, which transforms thermal energy, often from combustion of a fuel, into rotational energy. Most thermal power plants produce steam, and these are sometimes called steam power plants. Not all thermal energy can be transformed to mechanical power, according to the second law of thermodynamics. Therefore, thermal power plants also produce low-temperature heat. If no use is found for the heat, it is lost to the environment. If reject heat is employed as useful heat, for industrial processes or district heating, the power plant is referred to as a cogeneration power plant or CHP (combined heat-and-power) plant. In countries where district heating is common, there are dedicated heat plants called heat-only boiler stations. An important class of power stations in the Middle East uses by-product heat for desalination of water.

ClassificationThermal power plants are classified by the type of fuel and the type of

prime mover installed.

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By fuelNuclear power plants use a nuclear reactor’s heat to operate a steam

turbine generator.Fossil fuel powered plants may also use a steam turbine generator or

in the case of Natural gas fired plants may use a combustion turbine.Geothermal power plants use steam extracted from hot underground

rocks.Renewable energy plants may be fuelled by waste from sugar cane,

municipal solid waste, landfill methane, or other forms of biomass.In integrated steel mills, blast furnace exhaust gas is a low-cost,

although low-energy-density, fuel.Waste heat from industrial processes is occasionally concentrated

enough to use for power generation, usually in a steam boiler and turbine.By prime moverSteam turbine plants use the pressure generated by expanding steam

to turn the blades of a turbine.Gas turbine plants use the heat from gases to directly operate the

turbine. Natural-gas fuelled turbine plants can start rapidly and so are used to supply “peak” energy during periods of high demand, though at higher cost than base-loaded plants.

Combined cycle plants have both a gas turbine fired by natural gas, and a steam boiler and steam turbine which use the exhaust gas from the gas turbine to produce electricity. This greatly increases the overall efficiency of the plant, and most new base load power plants are combined cycle plants fired by natural gas.

Internal combustion Reciprocating engines are used to provide power for isolated communities and are frequently used for small cogeneration plants. Hospitals, office buildings, industrial plants, and other critical facilities also use them to provide backup power in case of a power outage. These are usually fuelled by diesel oil, heavy oil, natural gas and landfill gas.

Micro turbines, Stirling engine and internal combustion reciprocating engines are low cost solutions for using opportunity fuels, such as landfill gas, digester gas from water treatment plants and waste gas from oil production.

Cooling towers and waste heatBecause of the fundamental limits to thermodynamic efficiency of any

heat engine, all thermal power plants produce waste heat as a by-product of the useful electrical energy produced. Natural draft wet cooling towers at nuclear power plants and at some large thermal power plants are large hyperbolic chimney-like structures (as seen in the image at the left) that release the waste heat to the ambient atmosphere by the evaporation of water (lower left image).

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However, the mechanical induced-draft or forced-draft wet cooling towers (as seen in the image to the right) in many large thermal power plants, petroleum refineries, petrochemical plants, geothermal, biomass and waste to energy plants use fans to provide air movement upward through down coming water and are not hyperbolic chimney-like structures. The induced or forced-draft cooling towers are rectangular, box-like structures filled with a material that enhances the contacting of the up flowing air and the down flowing water.

In desert areas a dry cooling tower or radiator may be necessary, since the cost of make-up water for evaporative cooling would be prohibitive. These have lower efficiency and higher energy consumption in fans than a wet, evaporative cooling tower.

Where it is economically and environmentally possible, electric companies prefer to use cooling water from the ocean, or a lake or river, or a cooling pond, instead of a cooling tower. This type of cooling can save the cost of a cooling tower and may have lower energy costs for pumping cooling water through the plant’s heat exchangers. However, the waste heat can cause the temperature of the water to rise detectably. Power plants using natural bodies of water for cooling must be designed to prevent intake of organisms into the cooling cycle. A further environmental impact would be organisms that adapt to the warmer temperature of water when the plant is operating that may be injured if the plant shuts down in cold weather.


1. What is a power station or a power plant?2. How is mechanical power produced in thermal power stations?3. Which is the classification of thermal power plants?4. What is a nuclear power plant?5. What is a fossil fuel powered plant?6. What is a geothermal power plant?7. What is a renewable energy plant?8. What do steam turbine plants use?9. What about gas turbine plants and combined cycle plants?10.Why are power plants so important for the industry?

Look up and find the meaning of the words and the expressions:

commonwealthharnesscogenerationdesalination

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reciprocating enginesforced-draft cooling towersinduced-draft prime moverby-product heat


1. sample a. a device or devices randomly chosen from o lot of material. Sampling assumes that randomly selected devices will exhibit characteristics during testing that are typical of the lot as a whole

2. scaling b. a hardware device that is the central point, or one of them, for a network, a unit that provides services, share its resources and information with other computers, called clients, on a network

3. server c. the process of ending operation of a system or a subsystem, following a defined procedure

4. shutdown d. the name given to any telecommunications system involving the transmission of speech information, allowing two or more persons to communicate verbally

5. solvency e. a box into which a computer user can type text, usually in a word processor, within a formatting procedure or a graphic

6. telephony f. an operation performed by a digital processor to fill the screen with an image not being displayed in the native resolution of the LCD panel

7. text box g. an insidious and usually illegal computer program that masquerades as a program that is useful, fun or otherwise desirable for users to download to their system. Once the program is downloaded, it performs a destructive act

8. trojan horse h. abbreviation for Uninterruptible Power Supply, a standby power source that provides power to a server or other devices from a battery in the event of normal AC power failure

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9. UPS i. ability of a fluid to dissolve inorganic materials and polymers

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The Conditional Clauses

Conditionals are clauses introduced with if. There are three types of conditional clause: Type 1, Type 2 and Type 3. There is also another common type, Type 0. A. Type 0 – Conditionals: they are used to express something true; we can use when (whenever) instead of if and unless for if not.

Form:

If-clause Main clause if + Present Simple Present Simple

e.g. If you heat ice, it melts. If the temperature falls below 0°C, water turns into ice.

B. Type 1 – Conditionals: they are used to express real or very probable situations in the present or future.

Form:

If-clause Main clauseif + Present Simple Future bare

Present Continuous or (can/may/might/ Infinitive Present Perfect must/should/ could) Present Perfect Continuous

e.g. If you don’t study hard, you won’t go to the University.

C. Type 2 – Conditionals: they are used to express imaginary situations which are unlikely to happen in the present or future.

Form:

If-clause Main clause if + Past Simple would (could/might) + bare Infinitive Past Continuous

e.g. If I won the lottery, I would go on a trip around the world.

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D. Type 3 – Conditionals: they are used to express imaginary situations in the past, criticism or regrets.

Form:

If-clause Main clause if + Past Perfect would (could/might) + have + Past Participle Past Perfect Continuous

e.g. If John hadn’t missed the train, he wouldn’t have quarrelled with his boss.

Exercises:

1. Complete the Conditionals: 1. If the weather ….. (be) fine tomorrow, we will go to the swimming pool. 2. If you ….. (fill) in this form, I will process your application. 3. If he …… (pay) the fine, he will go to prison. 4. If you ….. (finish) your work, we can have dinner. 5. If you ……(not stop) laughing, you will have to leave. 6. If Pam ….. (call), tell him I’ll be late. 7. If I ….. (have) time, I would go to the seaside in the weekend.8. If I ….. (be) you, I would talk to my friend about the problem. 9. If he …… (study) harder, he would have passed the exam.10. If he ……(not be) so stupid, he would have been accepted.

2. Change the sentences using unless:

1. If you don’t go now, you will miss the flight. 2. If Tom wasn’t/weren’t here, we could have a party.3. If you don’t have an appointment you should come with me.4. We will not have dinner together if Mary doesn’t come on time.5. If your boss didn’t come to work, you could tell him you weren’t late.6. I wouldn’t trust him, if I didn’t know him.7. If he hadn’t known, he would have called us. 8. If Susan doesn’t find the book in the shops she will go to the library.9. If we don’t take care of the trees, the world’s climate will change.10. If we do not stop using aerosols we will destroy the ozone layer.11. If we don’t find some alternative sources of energy we won’t solve our environmental problems.12. If you don’t like the colour I could change it.

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3. Complete the sentences using Conditional rules:

1. Unless you …... (be) over eighteen, you ….. (join) this club.2. If you ….. (not burn) the dinner, we…..(not come) to this restaurant!3. If I ….. (not move) to Canada, I …..(never meet) you.4. If she ……(be) so busy, Sue ……(spend) more time with me.5. If she …… (have) the time, she ……(fly) to Rome.6. If I ……(see) Bob, I …..(tell) him the news.7. If he …… (change) the CD, he ……( crash) his car.8. If we ……(be) rich, we ….. (afford) an expensive car.9. If you ……(behave) yourself, we ……(go) to the Safari Park later.10. If you ……(see) Corrine ……(come) and …… (tell) me.


1 If you ...C... that pot, you will burn yourself.A will touch B would touch C touch

2 …….. you are busy, we shall talk later.A If B when C Unless

3 If you watch the news, you….. a lot to learn.A have B will have C would have

4 ……. you wear warm clothes, you won’t get cold.A Unless B If C Providing

5 If I were you, I ……. Jake to the party A would invite B will invite C have invited

6 …….the professor comes back now, what will you do?’A When B If C Supposing

7 If you……a seat, I will fetch the menu.A take B will take C have taken

8 If I ….. the bus, I wouldn’t have been late for work.’A haven’t miss B hadn’t missed C didn’t miss

5. Put the verbs in brackets in the appropriate tense:

1 If I were you, I ……(go out) in the snow.2 Michael would help you if he ……(be) here.3 If I ….. (close) the window, the storm would not have broken it.4 I …… (call) for help if I got luggage.5 Unless I knew the woman, I ……(talk) to her.6 If my boy had toothache, I ……(take) him to the dentist.7 Unless you ……(save) some money, you wouldn’t go on holiday.

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8 They would have changed their plans if they ….. (hear) the weather forecast.9 Emily would have sent a present if she …… (remember) their anniversary.10 They …… (help) us move the furniture if we ……(ask) them.11 If you…..(like) cream, you will like this cake.12 If Pam ….. (live) in the neighbourhood, you could invite her for dinner.13 Sarah ….. (join) us later unless she has work to do.14 Robbie ….. (feel) better if you invited him over.

6. Make sentences with the different meanings of the verb fall:

fall in love, fall to pieces, fall about, fall away, fall back, fall down, fall in, fall into, fall off, fall out, fall over, fall through, fall to.


1. Voi termina mai repede aceste dosare dacă mă vei ajuta.2. Dacă îmi explici acest exerciţiu voi face curăţenie în locul tău.3. Răniţii ar fi murit dacă echipajul salvării nu ar fi sosit la timp.4. Ana nu ar mai fi fost atât de supărată pe tine dacă ar fi ştiut adevărul.5. Dacă ar şti adresa noastră ar veni să ne viziteze.6. Dacă sora mea ar fi mers la universitate nu ar mai fi lucrat ca

asistentă acum. 7. Ar fi fost angajat la acea firmă până acum dacă ar fi avut calificarea

necesară.8. Nu îţi vei îmbunătăţi Engleza şi Spaniola dacă nu munceşti mai mult.

Optical fiber communications

Optical fiber communication is the method of transmitting information through optical fibers. Optical fibers can be used to transmit light and thus information over long distances. Nowadays, fiber-based systems have largely replaced radio transmitter systems for long-haul optical data transmission. They are largely used for telephony, but also for Internet traffic, long high-speed local area networks (LANs), cable-TV, and increasingly also for shorter distances.

Compared to systems based on electrical cables, the approach of optical fiber communications has advantages, the most important of which are:

The capacity of fibers for data transmission is huge: a single fiber can carry hundreds of thousands of telephone channels even without nearly

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utilizing the full theoretical capacity. In the last 30 years, the progress concerning transmission capacities of fiber links has been significantly faster than e.g. the progress in the speed or storage capacity of computers.

The losses for light propagating in fibers are amazingly small: about 0. 2 dB/km for modern single-mode fibers, so that many tens of kilometres can be bridged without amplifying the signals.

A large number of channels can be reamplified in a single fiber amplifier, if required for very large transmission distances.

Due to the achievable huge transmission rate, the cost per transported bit can be extremely low.

Compared to electrical cables, fiber-optic cables are very lightweight, so that the cost of laying a fiber-optic cable is much lower.

Fiber-optic cables are immune to problems of electrical cables such as ground loops or electromagnetic interference (EMI).

However, fiber systems are somewhat more sophisticated to install and operate, so that they tend to be less economical if their full transmission capacity is not required. Therefore, the ”last mile” (the connection to the homes and offices) and usually still bridged with electrical cables, while fiber-based communications do the bulk of the long-haul transmission. Gradually, however, fiber communications are used within metropolitan areas, and currently we see even the beginning of fiber to the home (FTTH), particularly in Japan, where private Internet users can already obtain affordable Internet connections with data rates of 100 Mbit/s – well above the performance of current ADSL systems, which use electrical telephone lines.

Optical fiber communications typically operate in a wavelength region corresponding to one of the following "telecom windows":

The first window at 800-900 nm was originally used. GaAs / AlGaAs-based laser diodes and light-emitting diodes (LEDs) served as senders, and silicon photodiodes were suitable for the receivers. However, the fiber losses are relatively high in this region, and fiber amplifiers are not well developed for this spectral region. Therefore, the first telecom window is suitable only for short-distance transmission.

The second telecom window utilizes wavelengths around 1.3 μm, where the fiber loss is much lower and the fiber dispersion is very small, so that dispersive broadening is minimized. This window was originally used for long-haul transmission. However, fiber amplifiers for 1.3 μm are not as good as their 1.5-μm counterparts based on erbium, and zero dispersion is not necessarily ideal for long-haul transmission, as it can increase the effect of optical nonlinearities.

The third telecom window, which is now very widely used, utilizes wavelengths around 1.5 μm. The fiber losses are lowest in this region, and erbium-doped fiber amplifiers are available which offer very high

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performance. Fiber dispersion is usually anomalous but can be tailored with great flexibility (dispersion-shifted fibers).


1. What is optical fiber communication?2. How can optical fibers be used?3. Which are the advantages of fiber communications?4. What are Telecom Windows?5. Which are the characteristics of the first window?6. What about the second and the third window?7. Why is optical fiber communication so important?

Look up and find the meaning of the words and the expressions:

optical fiberlong-haul optical databulkwavelengthbroadeningcounterpartserbiumerbium-doped fiberdispersion-shifted fiber


1. virtual address

a. the address of a location in virtual storage; a virtual address must be translated into a real address in order to process the data in processor storage

2. wireless b. a lens with variable focal length providing the ability to adjust the size on a screen by adjusting the zoom lens, instead of having to move the projector closer or further

3. wizard c. in a user interface, to progressively increase or decrease the size of a part of an image on a screen or in a window

4.workstation d. an insidious and usually illegal computer program that it designed to replicate itself over a network for the purpose of causing harm and / or destruction.

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5. worm e. a dialog within an application that uses step-by-step instructions to guide a user through a specific task

6. zoom f. the term refers to telecommunication in which electromagnetic waves, such as radio or television, to carry any communications signal from one section of a communications path to another

7. zoom lens g. a computer, usually used on a network or a scientific computer used for scientific application

8. cable assembly

h. a designated memory holding area that temporarily stores information copied or cut from a document, or files for transfer

9. clipboard i. fiber optic cable that has connectors installed on one or both ends

10.cluster j. a group of sectors on a hard drive that is addressed as one logical unit by the operating system. It is also the smallest contiguous area that can be allocated for the storage of data even if actual data require less storage

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Supplementary texts:

Other sources of energy

Other power stations use the energy from wave or tidal motion, wind, sunlight or the energy of falling water, hydroelectricity. These types of energy sources are called renewable energy.

Hydroelectricity: Hydroelectric dams impound a reservoir of water and release it through one or more water turbines to generate electricity.

Pumped storage: A pumped storage hydroelectric power plant is a net consumer of energy but decreases the price of electricity. Water is pumped to a high reservoir during the night when the demand, and price, for electricity is low. During hours of peak demand, when the price of electricity is high, the stored water is released to produce electric power. Some pumped storage plants are actually not net consumers of electricity because they release some of the water from the lower reservoir downstream, either continuously or in bursts.

Solar power: A solar photovoltaic power plant converts sunlight directly into electrical energy, which may need conversion to alternating current for transmission to users. This type of plant does not use rotating machines for energy conversion. Solar thermal electric plants are another type of solar power plant. They direct sunlight using either parabolic troughs or heliostats. Parabolic troughs direct sunlight onto a pipe containing a heat transfer fluid, such as oil, which is then used to boil water, which turns the generator. The central tower type of power plant uses hundreds or thousands of mirrors, depending on size, to direct sunlight onto a receiver on top of a tower. Again, the heat is used to produce steam to turn turbines. There is yet another type of solar thermal electric plant. The sunlight strikes the bottom of the pond, warming the lowest layer which is prevented from rising by a salt gradient. A Rankine cycle engine exploits the temperature difference in the layers to produce electricity. Not many solar thermal electric plants have been built. Most of them can be found in the Mojave Desert, although Sandia National Laboratory, Israel and Spain have also built a few plants.

Wind power: Wind turbines can be used to generate electricity in areas with strong, steady winds. Many different designs have been used in the past, but almost all modern turbines being produced today use the Dutch three-bladed, upwind design. Grid-connected wind turbines now being built are much larger than the units installed during the 1970’s, and so produce power more cheaply and reliably than earlier models. With larger turbines (greater than 100 kW), the blades move more slowly than older, smaller (less than 100 kW) units, which makes them less visually distracting and safer for airborne animals. However, the old turbines can

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still be seen at some wind farms, particularly at Altamont Pass and Tehachapi Pass.

Nuclear power plant: A nuclear power station: The nuclear reactor is contained inside the cylindrical containment buildings to the right - left is a cooling tower venting water vapour from the Non-Radioactive side of the plant.

A nuclear power plant (NPP) is a thermal power station in which the heat source is one or more nuclear reactors generating nuclear power.

Nuclear power plants are base load stations, which work best when the power output is constant (although boiling water reactors can come down to half power at night). Their units range in power from about 40 MWe to over 1000 MWe. New units under construction in 2005 are typically in the range 600-1200 MWe.

As of 2005 there are 443 licensed nuclear power reactors in the world, of which 441 are currently operational operating in 31 different countries. Together they produce about 17% of the world’s electric power.

Electricity was generated for the first time by a nuclear reactor on December 20, 1951 at the EBR-I experimental station near Arco, Idaho in the United States. On June 27, 1954, the world’s first nuclear power plant to generate electricity for a power grid started operations at Obninsk, USSR. The world’s first commercial scale power station, Calder Hall in England opened in 17 October, 1956.

Types of nuclear power plantsNuclear power plants are classified according to the type of reactor

used. However some installations have several independent units and these may use different classes of reactor. In addition, some of the plant-types below in the future may have passively safe features.

Fission reactors: Fission power reactors generate heat by nuclear fission of fissile isotopes of uranium and plutonium.

They may be further divided into three classes:Thermal reactors use a neutron moderator to slow or moderate

neutrons so that they are more likely to produce fission. Neutrons created by fission are high energy, or fast, and must have their energy decreased (be made thermal) by the moderator in order to efficiently maintain the chain reaction.

Fast reactors sustain the chain reaction without needing a neutron moderator. Because they use different fuel than thermal reactors, the neutrons in a fast reactor do not need to be moderated for an efficient chain reaction to occur.

Sub-critical reactors use an outside source of neutrons rather than a chain reaction to produce fission.

Fast reactors: Although some of the earliest nuclear power reactors were fast reactors, they have not as a class achieved the success of thermal

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reactors. Fast reactors have the advantages that their fuel cycle can use all of the uranium in natural uranium, and also transmute the longer-lived radioisotopes in their waste to faster-decaying materials. For these reasons they are inherently more sustainable as an energy source than thermal reactors. See fast breeder reactor. Because most fast reactors have historically been used for plutonium production, they are associated with nuclear proliferation concerns.

Fusion reactors: Nuclear fusion offers the possibility of the release of very large amounts of energy with a minimal production of radioactive waste and improved safety. However, there remain considerable scientific, technical, and economic obstacles to the generation of commercial electric power using nuclear fusion. It is therefore an active area of research, with very large-scale facilities such as JET, ITER, and the Z machine.

Advantages of nuclear power plants against other mainstream energy resources are: - no greenhouse gas emissions (during normal operation) - greenhouse gases are emitted only when the Emergency Diesel Generators are tested (the processes of uranium mining and of building and decommissioning power stations produce relatively small amounts); - does not pollute the air - zero production of dangerous and polluting gases such as carbon monoxide, sulphur dioxide, aerosols, mercury, nitrogen oxides, particulates or photochemical smog; - small solid waste generation (during normal operation); low fuel costs - because so little fuel is needed; - large fuel reserves - again, because so little fuel is needed; - nuclear batteries.

However, the disadvantages include: - risk of major accidents; - nuclear waste - high level radioactive waste produced can remain dangerous for thousands of years; - can help produce bombs; high initial costs; - high maintenance costs; -security concerns; high cost of decommissioning plants.

Telecommunication

Telecommunication is the transmission of signals over a distance for the purpose of communication. Today this process almost always involves the sending of electromagnetic waves by electronic transmitters but in earlier years it may have involved the use of smoke signals, drums or semaphores. Today, telecommunication is widespread and devices that assist the process such as the television, radio and telephone are common in many parts of the world. There is also a vast array of networks that connect these devices, including computer networks, public telephone networks, radio networks and television networks. Computer communication across the Internet, such as e-mail and internet faxing, is just one of many examples of telecommunication.

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The word telecommunication was adapted from the French word télécommunication. It is a compound of the Greek prefix tele- (τηλε-), meaning “far off”, and communication, meaning “exchange of information”.

The basic elements of a telecommunication system are:- a transmitter that takes information and converts it to a signal for

transmission- a transmission medium over which the signal is transmitted- a receiver that receives and converts the signal back into usable

informationFor example, consider a radio broadcast. In this case, the broadcast

tower is the transmitter, the radio is the receiver and the transmission medium is free space. Often telecommunication systems are two-way and devices act as both a transmitter and receiver or transceiver. For example, a mobile phone is a transceiver. Telecommunication over a phone line is called point-to-point communication because it is between one transmitter and one receiver; telecommunication through radio broadcasts is called broadcast communication because it is between one powerful transmitter and numerous receivers.

Signals can either be analogue or digital. In an analogue signal, the signal is varied continuously with respect to the information. In a digital signal, the information is encoded as a set of discrete values.

A collection of transmitters, receivers or transceivers that communicate with each other is known as a network. Digital networks may consist of one or more routers that route data to the correct user. An analogue network may consist of one or more switches that establish a connection between two or more users. For both types of network, a repeater may be necessary to amplify or recreate the signal when it is being transmitted over long distances. This is to combat noise which can corrupt the information carried by a signal.

A channel is a division in a transmission medium so that it can be used to send multiple independent streams of data. For example, a radio station may broadcast at 96 MHz while another radio station may broadcast at 94.5 MHz. In this case the medium has been divided by frequency and each channel received a separate frequency to broadcast on. Alternatively one could allocate each channel a segment of time over which to broadcast.

The shaping of a signal to convey information is known as modulation. Modulation is a key concept in telecommunications and is frequently used to impose the information of one signal on another. Modulation is used to represent a digital message as an analogue waveform. This is known as keying and several keying techniques exist – these include phase-shift keying, amplitude-shift keying and minimum-

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shift keying. Bluetooth, for example, uses phase-shift keying for exchanges between devices.

However, more relevant to earlier discussion, modulation is also used to boost the frequency of analogue signals. This is because a raw signal is often not suitable for transmission over free space due to its low frequencies. Hence its information must be superimposed on a higher frequency signal (known as a carrier wave) before transmission.

Early telecommunicationsEarly forms of telecommunication include smoke signals and drums.

Drums were used by natives in Africa, New Guinea and tropical America whereas smoke signals were used by natives in America and China. Contrary to what one might think, these systems were often used to do more than merely announce the presence of a camp.

In 1792, a French engineer, Claude Chappe built the first visual telegraphy (or semaphore) system between Lille and Paris. This was followed by a line from Strasbourg to Paris. In 1794, a Swedish engineer, Abraham Edelcrantz built a quite different system from Stockholm to Drottningholm. As opposed to Chappe’s system which involved pulleys rotating beams of wood, Edelcrantz’s system relied only upon shutters and was therefore faster. However semaphore as a communication system suffered from the need for skilled operators and expensive towers often at intervals of only ten to thirty kilometres (six to nineteen miles). As a result, the last commercial line was abandoned in 1880.

Telegraph and telephone

The first commercial electrical telegraph was constructed by Sir Charles Wheatstone and Sir William Fothergill Cooke. It used the deflection of needles to represent messages and started operating over thirteen miles (twenty-one kilometres) of the Great Western Railway on 9 April 1839. Both Wheatstone and Cooke viewed their device as “an improvement to the (existing) electromagnetic telegraph” not as a new device.

On the other side of the Atlantic Ocean, Samuel Morse independently developed a version of the electrical telegraph that he unsuccessfully demonstrated on 2 September 1837. Soon after he was joined by Alfred Vail who developed the register – a telegraph terminal that integrated a logging device for recording messages to paper tape. This was demonstrated successfully over three miles (five kilometres) on 6 January 1838 and eventually over forty miles (64 kilometres) between Washington, DC and Baltimore on 24 May 1844. The patented invention proved lucrative and by 1851 telegraph lines in the United States spanned over 20,000 miles (32,000 kilometres).

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The first transatlantic telegraph cable was successfully completed on 27 July 1866, allowing transatlantic telegraph communications for the first time. Earlier transatlantic cables installed in 1857 and 1858 only operated for a few days or weeks before they failed.

The conventional telephone was invented by Alexander Bell in 1876. Although in 1849 Antonio Meucci invented a device that allowed the electrical transmission of voice over a line. Meucci’s device depended upon the electrophonic effect and was of little practical value because it required users to place the receiver in their mouth to “hear” what was being said.

The first commercial telephone services were set-up in 1878 and 1879 on both sides of the Atlantic in the cities of New Haven and London. Bell held patents needed for such services in both countries. The technology grew quickly from this point, with inter-city lines being built and exchanges in every major city of the United States by the mid- 1880’s. Despite this, transatlantic communication remained impossible for customers until January 7, 1927 when a connection was established using radio. However no cable connection existed until TAT-1 was inaugurated on September 25, 1956 providing 36 telephone circuits.

Radio and television 1

In 1832, James Lindsay gave a classroom demonstration of wireless telegraphy to his students. By 1854 he was able to demonstrate a transmission across the Firth of Tay from Dundee to Woodhaven, a distance of two miles, using water as the transmission medium.

Addressing the Franklin Institute in 1893, Nikola Tesla described and demonstrated in detail the principles of wireless telegraphy. The apparatus that he used contained all the elements that were incorporated into radio systems before the development of the vacuum tube. However it was not until 1900, that Reginald Fessenden was able to wirelessly transmit a human voice. In December 1901, Guglielmo Marconi established wireless communication between Britain and the United States earning him the Nobel Prize in physics in 1909 (which he shared with Karl Braun).

On March 25, 1925, John Logie Baird was able to demonstrate the transmission of moving pictures at the London department store Selfridges. However his device did not adequately display halftones and thus only presented a silhouette of the recorded image. This problem was rectified in October of that year leading to a public demonstration of the improved device on 26 January 1926 again at Selfridges. Baird’s device relied upon the Nipkow disk and thus became known as the mechanical television. It formed the basis of experimental broadcasts done by the British Broadcasting Corporation beginning September 30, 1929.

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However for most of the twentieth century televisions depended upon the cathode ray tube invented by Karl Braun. The first version of such a television to show promise was produced by Philo Farnsworth and demonstrated to his family on September 7, 1927. Farnsworth’s device would compete with the work of Vladimir Zworykin who also produced a television picture in 1929 on a cathode ray tube. Zworykin’s camera, which later would be known as the Iconoscope, had the backing of the influential Radio Corporation of America (RCA) however eventually court action regarding “the electron image” between Farnsworth and RCA would resolve in Farnsworth’s favour.

Computer networks

On September 11, 1940 George Stibitz was able to transmit problems using teletype to his Complex Number Calculator in New York and receive the computed results back at Dartmouth College in New Hampshire. This configuration of a centralized computer or mainframe with remote dumb terminals remained popular throughout the 1950s. However it was not until the 1960s that researchers started to investigate packet switching – a technology that would allow chunks of data to be sent to different computers without passing through a centralized mainframe, first. A four - node network emerged on December 5, 1969 between the University of California, Los Angeles, the Stanford Research Institute, the University of Utah and the University of California, Santa Barbara. This network would become ARPANET, which by 1981 would consist of 213 nodes. In June 1973, the first non-US node was added to the network belonging to Norway’s NORSAR project. This was shortly followed by a node in London.

Telephone

Today, the fixed-line telephone systems in most residential homes remain analogue and, although short-distance calls may be handled from end-to-end as analogue signals, increasingly telephone service providers are transparently converting signals to digital before, if necessary, converting them back to analogue for reception. Mobile phones have had a dramatic impact on telephone service providers. Mobile phone subscriptions now outnumber fixed line subscriptions in many markets. Sales of mobile phones in 2005 totalled 816.6 million with that figure being almost equally shared amongst the markets of Asia/Pacific (204m), Western Europe (164m), CEMEA (Central Europe, the Middle East and Africa) (153.5m), North America (148m) and Latin America (102m). In terms of new subscriptions over the five years from 1999, Africa has

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outpaced other markets with 58.2% growth compared to the next largest market, Asia, which boasted 34.3% growth. Increasingly these phones are being serviced by digital systems such as GSM or W-CDMA with many markets choosing to depreciate analogue systems such as AMPS.

However there have been equally drastic changes in telephone communication behind the scenes. Starting with the operation of TAT-8 in 1988, the 1990s saw the widespread adoption of systems based around optic fibres. The benefit of communicating with optic fibres is that they offer a drastic increase in data capacity. TAT-8 itself was able to carry 10 times as many telephone calls as the last copper cable laid at that time and today’s optic fibre cables are able to carry 25 times as many telephone calls as TAT-8. This rapid increase in data capacity is due to several factors. First, optic fibres are physically much smaller than competing technologies. Second, they do not suffer from crosstalk which means several hundred of them can be easily bundled together in a single cable. Lastly, improvements in multiplexing have lead to an exponential growth in the data capacity of a single fibre. This is due to technologies such as dense wavelength-division multiplexing, which at its most basic level is building multiple channels based upon frequency division as discussed in the Technical foundations section. However despite the advances of technologies such as dense wavelength-division multiplexing, technologies based around building multiple channels based upon time division such as synchronous optical networking and synchronous digital hierarchy remain dominant.

Assisting communication across these networks is a protocol known as Asynchronous Transfer Mode (ATM). As a technology, ATM arose in the 1980s and was envisioned to be part of the Broadband Integrated Services Digital Network. The network ultimately failed but the technology gave birth to the ATM Forum which in 1992 published its first standard. Today, despite competitors such as Multiprotocol Label Switching, ATM remains the protocol of choice for most major long-distance optical networks. The importance of the ATM protocol was chiefly in its notion of establishing pathways for data through the network and associating a traffic contract with these pathways. The traffic contract was essentially an agreement between the client and the network about how the network was to handle the data. This was important because telephone calls could negotiate a contract so as to guarantee themselves a constant bit rate, something that was essential to ensure the call could take place without a caller’s voice being delayed in parts or cut-off completely.

Radio and television 2

The broadcast media industry is also at a critical turning point in its development, with many countries starting to move from analogue to

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digital broadcasts. The chief advantage of digital broadcasts is that they prevent a number of complaints with traditional analogue broadcasts. For television, this includes the elimination of problems such as snowy pictures, ghosting and other distortion. These occur because of the nature of analogue transmission, which means that perturbations due to noise will be evident in the final output. Digital transmission overcomes this problem because digital signals are reduced to binary data upon reception and hence small perturbations do not affect the final output.

In digital television broadcasting, there are three competing standards that are likely to be adopted worldwide. These are the ATSC, DVB and ISDB standards and the adoption of these standards thus far is presented in the captioned map. All three standards use MPEG-2 for video compression. ATSC uses Dolby Digital AC-3 for audio compression, ISDB uses Advanced Audio Coding (MPEG-2 Part 7) and DVB has no standard for audio compression but typically uses MPEG-1 Part 3 Layer 2. The choice of modulation also varies between the schemes. Both DVB and ISDB use orthogonal frequency-division multiplexing (OFDM) for terrestrial broadcasts (as opposed to satellite or cable broadcasts) where as ATSC uses vestigial sideband modulation (VSB). OFDM should offer better resistance to multi-path interference and the Doppler Effect (which would impact reception using moving receivers). However controversial tests conducted by the United States’ National Association of Broadcasters have shown that there is little difference between the two for stationary receivers.

In digital audio broadcasting, standards are much more unified with practically all countries (including Canada) choosing to adopt the Digital Audio Broadcasting standard (also known as the Eureka 147 standard).

However, despite the pending switch to digital, analogue receivers still remain widespread. Analogue television is still transmitted in practically all countries. For analogue, there are three standards in use. These are known as PAL, NTSC and SECAM. The basics of PAL and NTSC are very similar; a quadrature amplitude modulated sub-carrier carrying the chrominance information is added to the luminance video signal to form a composite video base-band signal (CVBS). The SECAM system, on the other hand, uses a frequency modulation scheme on its colour sub-carrier. The name "Phase Alternating Line" describes the way that the phase of part of the colour information on the video signal is reversed with each line, which automatically corrects phase errors in the transmission of the signal by cancelling them out. For analogue radio, the switch to digital is made more difficult by the fact that analogue receivers cost a fraction of the cost of digital receivers.

The Internet

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Today an estimated 15.7% of the world population has access to the Internet with the highest concentration in North America (68.6%), Oceania/Australia (52.6%) and Europe (36.1%). In terms of broadband access, countries such as Iceland (26.7 per 100), South Korea (25.4 per 100) and the Netherlands (25.3 per 100) lead the world. The International Telecommunication Union uses this information to compile a Digital Access Index that measures the overall ability of citizens to access and use information and communication technologies. Using this measure, countries such as Sweden, Denmark and Iceland receive the highest ranking while African countries such as Niger, Burkina Faso and Mali receive the lowest.

The history of the Internet dates back to the early development of communication networks. The idea of a computer network intended to allow general communication between users of various computers has developed through a large number of stages. The melting pot of developments brought together the network of networks that we know as the Internet. This included both technological developments and the merging together of existing network infrastructure and telecommunication systems.

The earliest versions of these ideas appeared in the late 1950s. Practical implementations of the concepts began during the late 1960s and 1970s. By the 1980s, technologies we now recognize as the basis of the modern Internet began to spread over the globe. In the 1990s the introduction of the World Wide Web (WWW) saw its use become commonplace.

The infrastructure of the Internet spread across the globe to create the world wide network of computers we know today. It spread throughout the Western nations and then begged a penetration into the developing countries, thus creating both unprecedented worldwide access to information and communications and a digital divide in access to this new infrastructure. The Internet went on to fundamentally alter and affect the economy of the world, including the economic implications of the dot-com bubble and offshore outsourcing of White-collar workers.

Before the InternetPrior to the widespread inter-networking that led to the Internet, most

communication networks were limited by their nature to only allow communications between the stations on the network. Some networks had gateways or bridges between them, but these bridges were often limited or built specifically for a single use. One prevalent computer networking method was based on the central mainframe method, simply allowing its terminals to be connected via long leased lines. This method was used in the 1950s by Project RAND to support researchers such as Herbert Simon,

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in Pittsburgh, Pennsylvania, when collaborating across the continent with researchers in Santa Monica, California, on automated theorem proving and artificial intelligence.

Networks that led to the Internet

ARPANET: Promoted to the head of the information processing office at ARPA, Robert Taylor intended to realize Licklider’s ideas of an interconnected networking system. Bringing in Larry Roberts from MIT, he initiated a project to build such a network. The first ARPANET link was established between the University of California, Los Angeles and the Stanford Research Institute on 21 November 1969. By 5 December 1969, a 4-node network was connected by adding the University of Utah and the University of California, Santa Barbara. Building on ideas developed in ALOHA net, the ARPANET started in 1972 and was growing rapidly by 1981. The number of hosts had grown to 213, with a new host being added approximately every twenty days.

ARPANET became the technical core of what would become the Internet, and a primary tool in developing the technologies used. ARPANET development was centred on the Request for Comments (RFC) process, still used today for proposing and distributing Internet Protocols and Systems. RFC 1, entitled “Host Software”, was written by Steve Crocker from the University of California, Los Angeles, and published on April 7, 1969.

Internet protocol suite

With so many different network methods, something needed to unify them. Robert E. Kahn of DARPA and ARPANET recruited Vint Cerf of Stanford University to work with him on the problem. By 1973, they had soon worked out a fundamental reformulation, where the differences between network protocols were hidden by using a common internetwork protocol, and instead of the network being responsible for reliability, as in the ARPANET, the hosts became responsible. Cerf credits Hubert Zimmerman and Louis Pouzin (designer of the CYCLADES network) with important work on this design.

With the role of the network reduced to the bare minimum, it became possible to join almost any networks together, no matter what their characteristics were, thereby solving Kahn’s initial problem. DARPA agreed to fund development of prototype software, and after several years of work, the first somewhat crude demonstration of what had by then become TCP/IP occurred in July 1977. This new method quickly spread across the networks, and on January 1, 1983, TCP/IP protocols became the

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only approved protocol on the ARPANET, replacing the earlier NCP protocol.

ARPANET to NSFNet

After the ARPANET had been up and running for several years, ARPA looked for another agency to hand off the network to; ARPA’s primary business was funding cutting-edge research and development, not running a communications utility. Eventually, in July 1975, the network had been turned over to the Defence Communications Agency, also part of the Department of Defence. In 1983, the U.S. military portion of the ARPANET was broken off as a separate network, the MILNET.

The networks based around the ARPANET were government funded and therefore restricted to non-commercial uses such as research; unrelated commercial use was strictly forbidden. This initially restricted connections to military sites and universities. During the 1980s, the connections expanded to more educational institutions, and even to a growing number of companies such as Digital Equipment Corporation and Hewlett-Packard, which were participating in research projects or providing services to those who were.

Another branch of the U.S. government, the National Science Foundation (NSF), became heavily involved in internet research and started development of a successor to ARPANET. In 1984 this resulted in the first Wide Area Network designed specifically to use TCP/IP. This grew into the NSFNet backbone, established in 1986, and intended to connect and provide access to a number of supercomputing centres established by the NSF.

The transition toward an Internet

It was around the time when ARPANET began to merge with NSFNet, which the term Internet originated, with "an internet" meaning any network using TCP/IP. "The Internet" came to mean a global and large network using TCP/IP, which at the time meant NSFNet and ARPANET. Previously "internet" and "internet work" had been used interchangeably, and "internet protocol" had been used to refer to other networking systems such as Xerox Network Services.

As interest in wide spread networking grew and new applications for it arrived, the Internet’s technologies spread throughout the rest of the world. TCP/IP’s network-agnostic approach meant that it was easy to use any existing network infrastructure, such as the IPSS X.25 network, to carry Internet traffic. In 1984, University College London replaced its transatlantic satellite links with TCP/IP over IPSS.

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Many sites unable to link directly to the Internet started to create simple gateways to allow transfer of e-mail, at that time the most important application. Sites which only had intermittent connections used UUCP or FidoNet and relied on the gateways between these networks and the Internet. Some gateway services went beyond simple e-mail peering, such as allowing access to FTP sites via UUCP or e-mail.

The first ARPANet connection outside the US was established to NORSAR in Norway in 1973, just ahead of the connection to Great Britain. These links were all converted to TCP/IP in 1982, at the same time as the rest of the Arpanet.

CERN, the European internet, the link to the Pacific and beyond

In 1984 the move in Europe towards more widespread use of TCP/IP started, and CERNET was converted over to using it. The TCP/IP CERNET remained isolated from the rest of the Internet, forming a small internal internet until 1989.

In 1988 Daniel Karrenberg, from CWI in Amsterdam, visited Ben Segal, CERN’s TCP/IP Coordinator; looking for advice about the transition of the European side of the UUCP Usenet network (much of which ran over X.25 links) over to TCP/IP. In 1987, Ben Segal had met with Len Bosack from the then still small company Cisco about TCP/IP routers, and was able to give Karrenberg advice and forward him on to Cisco for the appropriate hardware. This expanded the European portion of the Internet across the existing UUCP networks, and in 1989 CERN opened its first external TCP/IP connections. This coincided with the creation of Réseaux IP Européens (RIPE), initially a group of IP network administrators who met regularly to carry out co-ordination work together. Later, in 1992, RIPE was formally registered as a cooperative in Amsterdam.

At the same time as the rise of internetworking in Europe, ad-hoc networking to ARPA and in-between Australian colleges formed, based on various technologies such as X.25 and UUCPNet. These were limited in their connection to the global networks, due to the cost of making individual international UUCP dial-up or X.25 connections. In 1989, Australian colleges joined the push towards using IP protocols to unify their networking infrastructures. AARNet was formed in 1989 by the Australian Vice-Chancellors’ Committee and provided a dedicated IP based network for Australia.

The Internet began to penetrate Asia in the late 1980s. Japan, which had built the UUCP-based network JUNET in 1984, connected to NSFNet in 1989. It hosted the annual meeting of the Internet Society, INET’92, in Kobe. Singapore developed TECHNET in 1990, and Thailand gained a

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global Internet connection between Chulalongkorn University and UUNET in 1992.

A digital divide

While developed countries with technological infrastructures were joining the Internet, developing countries began to experience a digital divide separating them from the Internet. At the beginning of the 1990s, African countries relied upon X.25 IPSS and 2400 baud modem UUCP links for international and internet work computer communications. In 1996 a USAID funded project, the Leland initiative, started work on developing full Internet connectivity for the continent. Guinea, Mozambique, Madagascar and Rwanda gained satellite earth stations in 1997, followed by Côte d’Ivoire and Benin in 1998.

In 1991 China saw its first TCP/IP college network, Tsinghua University’s TUNET. China went on to make its first global Internet connection in 1994, between the Beijing Electro-Spectrometer Collaboration and Stanford University’s Linear Accelerator Center. However, China went on to implement its own digital divide by implementing a country-wide content filter.

Opening the network to commerce

The interest in commercial use of the Internet became a hotly debated topic. Although commercial use was forbidden, the exact definition of commercial use could be unclear and subjective. Everyone agreed that one company sending an invoice to another company was clearly commercial use, but anything less was up for debate. UUCPNet and the X.25 IPSS had no such restrictions, which would eventually see the official barring of UUCPNet use of ARPANET and NSFNet connections. Some UUCP links still remained connecting to these networks however, as administrators cast a blind eye to their operation.

During the late 1980s, the first Internet service provider (ISP) companies were formed. Companies like PSINet, UUNET, Netcom, and Portal Software were formed to provide service to the regional research networks and provide alternate network access, UUCP-based email and Usenet News to the public. The first dial-up ISP, world.std.com, opened in 1989.

This caused controversy amongst university users, who were outraged at the idea of non-educational use of their networks. Eventually, it was the commercial Internet service providers who brought prices low enough that junior colleges and other schools could afford to participate in the new arenas of education and research.

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By 1990, ARPANET had been overtaken and replaced by newer networking technologies and the project came to a close. In 1994, the NSFNet, now renamed ANSNET (Advanced Networks and Services) and allowing non-profit corporations access, lost its standing as the backbone of the Internet. Both government institutions and competing commercial providers created their own backbones and interconnections. Regional network access points (NAPs) became the primary interconnections between the many networks and the final commercial restrictions ended.

Email and Usenet – The growth of the text forum

E-mail is often called the killer application of the Internet. However, it actually predates the Internet and was a crucial tool in creating it. E-mail started in 1965 as a way for multiple users of a time-sharing mainframe computer to communicate. Although the history is unclear, among the first systems to have such a facility were SDC’s Q32 and MIT’s CTSS.

The ARPANET computer network made a large contribution to the evolution of e-mail. There is one report indicating experimental inter-system e-mail transfers on it shortly after ARPANET’s creation. In 1971 Ray Tomlinson created what was to become the standard Internet e-mail address format, using the @ sign to separate user names from host names.

A number of protocols were developed to deliver e-mail among groups of time-sharing computers over alternative transmission systems, such as UUCP and IBM’s VNET e-mail system. E-mail could be passed this way between a number of networks, including ARPANET, BITNET and NSFNet, as well as to hosts connected directly to other sites via UUCP.

In addition, UUCP allowed the publication of text files that could be read by many others. The News software developed by Steve Daniel and Tom Truscott in 1979 was used to distribute news and bulletin board-like messages. This quickly grew into discussion groups, known as newsgroups, on a wide range of topics. On ARPANET and NSFNet similar discussion groups would form via mailing lists, discussing both technical issues and more culturally focused topics.

A world library – From gopher to the WWW

The first World Wide Web server, currently in the CERN museum, labelled "This machine is a server. DO NOT POWER DOWN!!"

As the Internet grew through the 1980s and early 1990s, many people realized the increasing need to be able to find and organize files and information. Projects such as Gopher, WAIS, and the FTP Archive list attempted to create ways to organize distributed data. Unfortunately, these

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projects fell short in being able to accommodate all the existing data types and in being able to grow without bottlenecks.

One of the most promising user interface paradigms during this period was hypertext. The technology had been inspired by Vannevar Bush’s "memex" and developed through Ted Nelson’s research on Project Xanadu and Douglas Engelbart’s research on NLS. Many small self-contained hypertext systems had been created before, such as Apple Computer’s HyperCard.

In 1991, Tim Berners-Lee was the first to develop a network-based implementation of the hypertext concept. This was after Berners-Lee had repeatedly proposed his idea to the hypertext and Internet communities at various conferences to no avail - no one would implement it for him. Working at CERN, Berners-Lee wanted a way to share information about their research. By releasing his implementation to public use, he ensured the technology would become widespread. Subsequently, Gopher became the first commonly-used hypertext interface to the Internet. While Gopher menu items were examples of hypertext, they were not commonly perceived in that way.

An early popular web browser, modelled after HyperCard, was ViolaWWW. It was eventually replaced by, Mosaic in terms of popularity. Mosaic a graphical browser for the WWW, was developed by a team at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign (NCSA-UIUC), and led by Marc Andreessen. Funding for Mosaic came from the High-Performance Computing and Communications Initiative, a funding program initiated by then-Senator Al Gore’s High Performance Computing Act of 1991. Mosaic’s graphical interface soon became more popular than Gopher, which at the time was primarily text-based, and the WWW became the preferred interface for accessing the Internet. The World Wide Web has led to a widespread culture of individual self publishing and co-operative publishing.

Finding what you need – The search engine

Even before the World Wide Web, there were search engines that attempted to organize the Internet. The first of these was the Archie search engine from McGill University in 1990, followed in 1991 by WAIS and Gopher. All three of those systems predated the invention of the World Wide Web but all continued to index the Web and the rest of the Internet for several years after the Web appeared. There are still Gopher servers as of 2006, although there are a great many more web servers.

As the Web grew, search engines and Web directories were created to track pages on the Web and allow people to find things. The first full-text

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Web search engine was WebCrawler in 1990. Before WebCrawler, only Web page titles were searched. Another early search engine, Lycos, was created in 1993 as a university project, and was the first to be commercially successful. By August 2001, Google tracked over 1.3 billion web pages and the growth continues, although the real advances are not in terms of database size, but relevancy ranking, the methods by which search engines attempt to sort the best results first. Algorithms for this have continuously improved since circa 1996, when it became a major issue, due to the rapid growth of the web, which made it impractical for searchers to look through the entire list of results. As of 2006 the rankings are more important than ever, since looking through the entire list of results is not so much impractical as humanly impossible, since for popular topics new pages appear on the web faster than anyone could read them all. Google’s Page Rank method for ordering the results has received the most press, but all major search engines continually refine their ranking methodologies with a view toward improving the ordering of results.

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IRREGULAR VERBS

Infinitive Past Tense Past Participle

Translation of the Infinitive

arise arose arisen a se ridica

awake awoke awoken a se trezi

be was/were been a fi

bear bore born/borne a purta, a naşte

beat beat beaten a bate

become became become a deveni

begin began begun a începe

bend bent bent a (se) îndoi

bet bet bet a paria

bind bound bound a lega

bit bit bit/bitten a muşca

bleed bled bled a sângera

blow blew blown a sufla, a bate

break broke broken a (se) sparge

breed bred bred a creste, a educa

bring brought brought a aduce

build built built a construi

burn burnt burnt a arde

burst burst burst a izbucni, a năvăli

buy bought bought a cumpăra

cast cast cast a arunca

catch caught caught a prinde

choose chose chosen a alege

cling clung clung a se agăţa

come came come a veni

cost cost cost a costa

creep crept crept a se târî, a se furişa

cut cut cut a tăia

deal dealt dealt a trata, a se ocupa de

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dig dug dug a săpa

do did done a face

draw drew drawn a trage, a desena

dream dreamt dreamt a visa

drink drank drunk a bea

drive drove driven a mâna, a şofa

eat ate eaten a mânca

fall fell fallen a cădea

feed fed fed a hrăni

feel felt felt a (se) simţi

fight fought fought a (se) lupta

find found found a găsi

fly flew flown a zbura

forbid forbade forbidden a interzice

forecast forecast forecast a prevedea

forget forgot forgotten a uita

forgive forgave forgiven a ierta

freeze froze frozen a îngheţa

get got got a primi, a obţine

give gave given a da

go went gone a merge

grind ground ground a măcina

grow grew grown a creşte

hang hung hung a atârna

have had had a avea

hear heard heard a auzi

hide hid hid/hidden a (se) ascunde

hit hit hit a lovi

hold held held a ţine

hurt hurt hurt a răni, a durea

keep kept kept a tine, a păstra

kneel knelt knelt a îngenunchea

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knit knit knit a tricota

know knew known a şti, a cunoaşte

lay laid laid a pune, a aşeza

lead led led a conduce

lean leant leant a se apleca/sprijini

leap leapt leapt a sări

learn learnt learnt a învăţa

leave left left a pleca, a lăsa

lend lent lent a da cu împrumut

let let let a lăsa, a permite

lie lay lain a zăcea, a se afla

light lit lit a aprinde

lose lost lost a pierde

make made made a face

mean meant meant a însemna

meet met met a (se) întâlni

pay paid paid a plăti

put put put a pune

read read read a citi

ride rode ridden a călări

ring rang rung a suna

rise rose risen a răsări, a se ridica

run ran run a fugi

saw sawed sawn a tăia cu ferăstrăul

say said said a spune

see saw seen a vedea

seek sought sought a căuta

sell sold sold a vinde

send sent sent a trimite

set set set a pune

sew sewed sewn a coase

shake shook shaken a scutura, a tremura

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shine shone shone a străluci

shoot shot shot a împuşca, a filma

show showed shown a arăta

shrink shrank shrunk a se strânge

shut shut shut a include

sing sang sung a cânta

sink sank sunk a (se) scufunda

sit sat sat a şedea

smell smelt smelt a mirosi

sow sowed sown a semăna

speak spoke spoken a vorbi

speed sped sped a grăbi, a accelera

spell spelt spelt a ortografia

spend spent spent a cheltui, a petrece

spill spilt spilt a vărsa

spin spun spun a toarce

spit spat spat a scuipa

split split split a despica

spoil spoilt spoilt a răsfăţa

spread spread spread a (se) întinde

spring sprang sprung a izvorî, a sari

stand stood stood a sta (în picioare)

steal stole stolen a fura, a (se) furişa

stick stuck stuck a lipi

sting stung stung a înţepa

stink stunk stunk a mirosi urât

strike struck struck a lovi

string strung strung a înşira (pe o aţă)

strive strove striven a năzui

swear swore sworn a jura, a înjura

sweat sweat sweat a transpira

sweep swept swept a mătura

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swell swelled swollen a se umfla

swim swam swum a înota

swing swung swung a legăna

take took taken a lua

teach taught taught a învăţa (pe altul), a preda

tear tore torn a rupe, a sfâşia

tell told told a spune, a povesti

think thought thought a (se) gândi

throw threw thrown a arunca

thrust thrust thrust a înfige

understand understood understood a înţelege

wake woke woken a trezi

wear wore worn a purta

weave wove woven a ţese

weep wept wept a plânge

win won won a câştiga

wind wound wound a răsuci

withdraw withdrew withdrawn a (se) retrage

wring wrung wrung a stoarce

write wrote written a scrie

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Popa, Gabriela / Popa, Ion Florin / Rizescu, Cristina / Gheorghe, Gheorghe – Dicţionar tehnic în limba engleză, Editura Bibliotheca, Târgovişte, 2004.

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Texts used and adapted for reading and vocabulary exercises: http://en.wikipedia.org

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C u r s - English for Engineering

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