—Tom can’t find his gloves. Are these blue gloves his?

      —No, they ______ be his. His gloves are black.

A. must            B. may            C. can’t               D. mustn't

You mustn't cross the street while the red traffic lights are on．Which of the following is the same in meaning？

1. A.
   You must walk slowly across the street when the red traffic lights are on．
2. B.
   You can't go across the street before the traffic lights change to red．
3. C.
   You don't have to wait when you want to go to the other side of the street though the traffic lights remind you not to do so．
4. D.
   Don't go across the street before the traffic lights change to green．