—Mr Smith must have been to your home this morning．
—No, he ______, because he didn’t know my address．
A. couldn’t B. can C. mustn’t D. may not
—How was the youth club last night, Mark?
— It was great fun. You come.
A. must B. can C. should D. may
—Is this John’s T-shirt?
—It_______be his. It`s much too small for him.
A. needn’t B. shouldn’t C. can’t D. must
The desk is not dirty．You ________ clean it．
A. mustn’t
B. shouldn’t
C. needn’t
D. can’t
— Can I go to the movie, Mum?
— Certainly. But you _______ be back by ten o’clock.
A. can B. may C. might D. must
Trees ____ fight air pollution．They are natural air conditioners．
A. should B. must C. need D. can
