1. I think you had better give up smoking immediately
2. It's very inconvenient if you are not able to drive
3. Do I have to bring you my passport?
4. John can’t be the thief.
5. The cat must be in the house somewhere.
6. That must be david who rings the phone
7. Anna should win the race tomorrow
8. The letter could be from my cousin, Janice
9. That can't be Colin because he is in holiday
10. She must be going to a fancy-dress party
11. your hairbrush might be in the living room
12. Harriet should be here in half an hour
13.James could be in trouble at school