(   )28.－_____ you put away your books?
－Yes, mum. I’ll do it at once.

— I think the man over there must be Bob.
— It _______ be him. He has gone to England.

— Must I feed the goldfish now?
— No, you ______. But you must do it before supper.

Sometimes we have much homework to do, but not often. Anyway, it ______in time.

–Whose notebook is this? Is it Julie’s?
–It _________be hers, she has gone to Beijing.
A. must                 B. mustn’t                 C. can’t

–Look at that girl! Is it Susan?
--No, it _______ be her. She has gone back to her hometown.

---______ you able to run faster than Peter?    --- Oh, I’m not sure.
A. Can                  B. Are                    C. Will

—I want to know if I _______________smoke here.
—No, you ______________. Could you see the sign “ No Smoking” there?

A: Listen! Is it Linda singing in the next room?
B: No, it __________ be her. She is still in Shanghai.

He ________be at home because the light in his room is on.