1. At this time last year, they (build) this house. 
were building
2. I (drive) my car very fast when you called me. 
was driving
3. I (chat) with my friends while my teacher (teach) the lesson yesterday. 
was chatting, was teaching
4. My father (watch) TV when I got home. 
was watching
5. At this time yesterday, I (prepare) for my son’s birthday party. 
was preparing
6. What you (do) at 8 pm yesterday? 
were you doing
7. Where you (go) when I saw you last weekend? 
were you going
8. They (not go) to school when I met them yesterday. 
weren't going||were not going
9. My mother (not do) the housework when my father came home. 
wasn't doing||was not doing
10. My sister (read) books while my brother (play) football yesterday afternoon. 
was reading, was playing
1. At this time last year, they (build) this house. were building
2. I (drive) my car very fast when you called me. was driving
3. I (chat) with my friends while my teacher (teach) the lesson yesterday. was chatting, was teaching
4. My father (watch) TV when I got home. was watching
5. At this time yesterday, I (prepare) for my son’s birthday party. was preparing
6. What you (do) at 8 pm yesterday? were you doing
7. Where you (go) when I saw you last weekend? were you going
8. They (not go) to school when I met them yesterday. weren't going||were not going
9. My mother (not do) the housework when my father came home. wasn't doing||was not doing
10. My sister (read) books while my brother (play) football yesterday afternoon. was reading, was playing
