1) be bound to certain or likely to happen

2) judging by appearances to make judgements based on the way sb/sth looks

3) the apple of somebody's eye a person or thing that is loved more than any other

4) day in, day out happening every day

5) once in a blue moon very rarely

6) come to an end to end; to stop)

7) go off the deep end to suddenly become very angry or emotional

8) miss the boat to fail to use an opportunity

9) all of a sudden suddenly

10) have one's heart set on to desire greatly, to be determined to

11) keep your fingers crossed to hope for good news

12) come out of your shell to become less shy and more confident

13) in full swing having reached a very lively level

14) head over heels in love loving somebody very much

15) Keep up with the Joneses to want the same things that other people have

16) over the hill old and therefore no longer useful or attractive

17) be in the same boat to be in the same difficult situation

18) bark up the wrong tree to make the wrong choice and waste one's effort

19) come rain or shine no matter how hard it is to do

20) in the nick of time just in time before something bad happens