1 - C) walk on air - be very happy
2 - D) fill one is blue in the face - try hard
3 - B) - sleep on it - postpone a decision till next morning
4 - F) - read between the lines - find or understand the implied meaning
5 - A) - on the carpet - called in by the boss for criticism
6 - E) - take a stand on something - make a firm opinion on smth.