Ответ:

1. broke

2. wasn't watching

3. heard, was doing

4. did...get

5. were...doing

6. prepared, were doing

7. watered

8. was having, knock

9. went

10. did you get

11. studied, was playing

12. visited

13. didn't, was

14. weren't skating

15. phoned, didn't answer

Не эксперт, мог где-то сделать ошибку, но думаю они здесь отсутствуют