Réponse :
1. When I saw him, he was doing his homework.
2. We were waiting for Sally. She was late.
3. He stoped working in the garden when the phone rang.
4. They took her bag while she wasn't/was not looking.
5. I didn't/did not break, it was Tom.
6. How long ago did you start learning English ? + I started learning English... year(s) ago.
7. How fast was he driving when the police stoped him ?
8. Was it raining when you got up ?
9. What time did the post come this morning ?
10. He broke his ankle playing football.
11. They were sleeping when the doorbell rang.