Ответ:
1. I saw a light in your window as I <u>was passing</u> by.
b) was passing (Past Continuous)
2. Yesterday as I was walking down Cherry Lane, I <u>met</u><u> </u>Thomas, an old friend of mine.
a) met (Past Simple)
3. Liz's elder brother said that he <u>was going</u><u> </u>to enter Leeds University.
b) was going (Past Continuous)
4. While my son <u>was waiting</u> for my call, somebody knocked at the door.
b) was waiting (Past Continuous)
5. We <u>were just talking</u><u> </u>about him when he suddenly <u>came</u><u> </u>in.
b) were just talking (Past Continuous)
a) came in (Past Simple)
6. Yesterday while Dad <u>was shaving</u>, he <u>cut</u> himself slightly.
b) was shaving (Past Continuous)
a) cut (Past Simple)
7. They <u>quarreled</u> while they <u>were washing</u><u> </u>their car.
a) quarreled (Past Simple)
b) were washing (Past Continuous)