Ответ:
1. mice
2. a) These apples are red.
3. c) My father doesn’t work at this factory.
4. b) Students are writing a test now.
5. a) What foreign languages does our teacher know?
6. c) I watch TV every day, do not I?
7. a) Yesterday I ate at the restaurant.
8. b) I didn’t tell anybody about it.
9. b) My brother likes to do everything by himself.
10. c) had to
11. a) Two letters were written by him.
12. b) He likes swimming. – Gerund.