1. was waiting/ arrived
2. Was he going/ saw
3. Phoned
4.was talking/ walked
5. Did she know/ were coming
6. Were sitting/ arrived
7. Met / was shopping
8. Arrived/ was leaving
9. Were making/ didn't hear
10. Were walking/started
11.started/ were driving
12.met/ were working
13. Did she arrived
14.broke/was playing
15. Didn't like/ was studying.
16.cut/ was chopping
17. Was leaving
18. Drove
19. Were you doing
20. Went/ were staying