Matching Pairs COMMON IDIOMS IN ENGLISHOnline version A short list of common idioms in English. by kepa olaizola garcia 1 Take it easy. 2 Let the cat out of the bag. 3 Break a leg. 4 Sleep on it. 5 Hit the nail on the head. 6 You can´t judge a book by its cover. 7 Costs an arm and a leg. 8 Hit the books. 9 When pigs fly. 10 Piece of cake. To study. You shouldn´t decide upon something based just on outward appearances. Something will never happen. Relax Good luck. To disclose a secret that was supposed to be kept. Something is very easy. Something is very expensive. Something that is precisely right. To think.