Ответ:
1. I saw you in the park yesterday, you were sittingon a bench
2.they were travelling to Canada when they met each other
3.while i was listening to music, my brotherwas doing his homework
4.what were you writing when your computer crashed?
5.as he passed the bank, a man in a maskknocked him onto the ground
6.tom arrived while the children were having their bath
7.he was coming while i was having a breakfast
8. what were you doing at 10 o'clock on Sunday?
9.what were you doing when the phone rang?
10.while she was cooking dinner, she cut her finger