—Listen ! Helen is singing in the next room.—It _______ be Helen. She has gone to Beijing.
#74851
A
can’t
B
mustn’t
C
may
D
should
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You_____ all those calculations! We have a computer to do that sort of thing.
#63501
A
needn’t have done
B
must not have done
C
shouldn’t have done
D
can not have done
The light in his office is out. He_________ left for home.
#62358
A
must have
B
must have been
C
should have
D
should have been