—Listen ! Helen is singing in the next room.—It __________ be Helen. She is in Tianjin now.   
#76500
A
can’t
B
mustn’t
C
may not
D
shouldn’t
推荐题目
--- Can you make a kite for me?--- Sorry, I _____.
#75948
A
needn’t
B
can’t
C
mustn’t
D
shouldn’t
I’m sorry, Bill. I _________ the book to you last week, but I was so busy that I forgot to do so.
#63435
A
must have returned
B
could return
C
should have returned
D
might return
They       have got lost, or had an accident.
#62726
A
can
B
might
C
must
D
mustn’t