3.You must....
4. I'm sure....
5. Can/May I....
6. The students must...
7. They must be at....
8. Can you...
9. These men may/can be criminals.
10.
11. Maybe David...
12. You mustn't park here.
2)
1. must
2. must
3. may
4. can
5. could
6. mustn't
7.needn't
8. must
9. can
10 must