1. have to
2. don't have to
3. mustn't
4. mustn't
5. don't have to
6. don't have to
7. must
8. must
9. must
10. have to
11. don't have to
12. must
13. mustn't
14. don't have to
15. must
16. don't have to
17. don't have to
18. have to, mustn't
19. don't have to
20. mustn't