1. was explaining

2. met

3. was listening

4. started

5. exploded

6. appeared

7. increased

8. visited, bought

9. were cleaning

10. was cleaning

11. lived

12. was taking

13. arrived

14. were driving

15. dropped

16. did, was doing

17. found, was having

18. won, bought

19. was working

20. got, was

21. were swimming