51、 ________at the door before you come into the room.
A．Hit
B．Knock
C．Touch
D．Strike


52、Hospital doctors don't go out very often as their work_________ all their time.
A．takes away
B．takes in
C．takes over
D．takes up

53、 Say________ what you mean and then there will be no misunderstanding.
A．casually
B．eventually
C．necessary
D．precisely


54、 All their attempts to_________ the child from the burning building were in vain.
A．regain
B．recover
C．rescue
D．reserve


55、 The story was said to have been based on the information from a reliable_________
A．source
B．foundation
C．origin
D．basis


56、
He never wrote to his father_________ he was in need of money.
A．except
B．except when
C．except for
D．except that


57、 Stressful environments lead to unhealthy such as poor eating habits,which _________increase the risk of heart disease.
A．in turn
B．in return
C．by chance
D．by turns


58、 I' ve been working on my vocabulary actively, and one way to_________ it is to see films in
English on TV.
A．go down
B．go up
C．improve
D．decrease


59、According to the American federal government, residents of Hawaii have the longest life _________
A．scope
B．rank
C．span
D．scale


60、
You may_________ this; I don' t want it back.
A．get
B．remain
C．maintain
D．keep