—–I think the man over there must be Tom.—–It _____ be him. He has ______ to America.

Food safety is important. Rules        to stop people from food pollution.

）The red bike _______be Hu’s.  She has a blue bike.

—Dad, must I finish my homework today?—No, you ______. You may do it tomorrow.

 --- Do we have to hand in our research reports this afternoon, Professor Smith?--- Yes, you _______ . I will be waiting to check them all the afternoon.