Bai I.
11. had explained
12. stopped
13. were
14. do/ were
15. were
16. were not
17. would spend
18. had
19. understood
20. spoke

Bài I
21. had decided
22. would have called
23. had understood
24. has/ won't write
25. told/ would buy
26. had given
27. had permitted
28. would have told
29. knew/ wouldn't buy
30. had studied

Bài I.
31. stay/ will have lived
32. leaves/ will ask
33. drives/ must be
34. work/ will probably need
35. didn't snow/ would go
36. would have gone
37. will be
38. was/ would be
39. manage, will drive
40. would have been/ hadn't known

Bài II.
1. I'll call the police unless you leave me alone
2. If the weather weren't snowy, we would go to school
3. If you press this button, the machine will stop 
4. If you make me some coffee, I'll give you one of my biscuits

Bài I.
1. paint
2. hears
3. see
4. will accept
5. gets
6. will steal
7. writes
8. do/ will have
9. will give