đổi các câu sau thành câu bị động 

1. You must return those books to the library soon.
2. Did you do your exercises perfectly ?
3. Do they prepare their lessons carefully ?
4. Who has written that novel ?
5. People play football all over the word.
6. My sister is writing that note in her notebook.
7. They keep those maps on the shelves for reference.
8. They have just told us about that.
9. They gave my little sister a ticket.
10. People say he is jealous of her.
11. They believed that he was innocent.
12. People know that he is armed.
13. We know that you were in town on the night of the crime.
14. We considered that she was the best singer at that time.
15. They say he was a spy.
16. People rumored that the coming crop was the worst.
17. People say that prevention is better than cure.
18. People believe that he was killed.
19. They reported that the expedition reached the South Pole in May.
20. They have invited all the members to the party.