Делала по правилам согласования времен и наречий, так что вроде всё должно быть правильно
1. They said that the previous year they had spent in the Crimea
2. They said that they had moved to a new flat the day before
3. He said that he didn't remember what she had said
4. They said that they had seen him that day twice
5. She said that she should help me if I liked
6. He said that he had been translating that text for two hours
7. Beth said that they were watching us at the moment
8. His farther said that he would be retired the next month
9. Our teacher said that we had to be more polite. (здесь, я так понимаю, опечатка была?)
10. My friend said that he was not doing anything special then, he was watching TV
11. Her mother said that she would go for a walk if she had time
12. Nick said that he had not told anybody about it
13. Polly said that it would be nice of you if you apologized for your behaviour
14. His friend said that he was going to go to university
15. My parents said that I would fail my exams if I didn't work hard
16. She said that two years before they had been students
17. Kate said that the next year she would go to the USA
18. The pupil said that he had not been at school the day before as he had been ill
19. His teacher said that he thought he would become a singer as he sang well.
20. They said that they were not sure she had already finished her work