a feather in one's cap	an accomplishment or achievement that one may justly be proud of
birds of a feather (flock together)	people of the same sortv(will be found together)
show the white feather	show fear or cowardice in a particular situation
to feather one's nest	to make things comfortable for oneself, enrich oneself (sometimes dishonestly)
to grow up	become adult
to look through	revise, examine (papers), look for information
to stand in (for sb)	take the place of
to take up	begin a hobby, sport or kind of study
to turn out	to develop
to work up	excite, stir up
in a blue mood, to feel blue, to have the blues	to be sad or miserable
out of the blue	unexpectedly
to blue pencil	to censor
once in a blue moon	rarely or never
a blue film	an obscene or pornographic film
a blue-collar worker	a manual or factory worker (white collar worker=office worker)
to beat someone black and blue	to hit someone so that s/he has many bruises