IDIOM 1:"go under the knife" -> MEANING: to be operated on in surgery -> EXAMPLE: His wife went under the knife at the hospital last evening.
IDIOM 2:"pull through " -> MEANING: recover from a serious illness -> EXAMPLE: The car accident was very bad and I don't think that the driver will pull through.
IDIOM 3:"under the weather" -> MEANING: not feeling well -> EXAMPLE: My boss has been feeling under the weather all week and has not come to work during that time.
IDIOM 4:"feel on top of the world" -> MEANING: feel very healthy -> EXAMPLE: I have been feeling on top of the world since I quit my job.
IDIOM 5:"head shrinker " -> MEANING: a psychiatrist -> EXAMPLE: The man was told to go and see a head shrinker after he threatened the woman in the store several times.