Ответ:
1. She cooked yesterday.
2. She was cooking at three o'clock yesterday.
3. She was cooking from two till four yesterday.
4. I was not reading at five o'clock.
5. I was not reading when you came in.
6. What did he do when I came?
7. What was he doing the whole day yesterday?
8. Pete watered flowers in the garden yesterday.
9. Pete was watering flowers in the garden at five o'clock yesterday.
10. What was Pete doing when I came to see him?