I. Choose the correct word or phrase in each sentence.
1. There’s someone at the door. It can / must be the postman.
2. Don’t worry, you don’t have to / mustn’t pay now.
3. It was 5 o’clock an hour ago. Your watch can’t / mustn’t be right.
4. In my opinion, the government might / should do something about this.
5. I suppose that our team must / should win, but I’m not sure.
6. I think you had better / would better take a pullover with you.
7. Sorry, I can’t stay any longer. I have to / might go.
8. It’s a school rule, all the pupils have to / must wear a uniform.
9. Let’s tell Anna. She could / might not know.
10. Jones could / must be president if Smith has to resign.