Odpowiedź:
1. You don't have to go.
2. Can I open the window?
3. Can you sit?
4. He should learn.
5. I have to work tommorow.
9. Students have to learn.
10. Students mustn't smoke.
11. She can swim a lot of time.
12. I can work.
13. I shouldn't eat.
14. I don't have to work tommorow.
15. Do we must work tommorow.
16. Can you speak english?
17. Can he play piano?