1. They (to drink) tea when I (to come) home.
2. He (to walk) along the river when a boat (to pass).
3. The old man (to think) about his plan when he (to fall) asleep.
4. We (to listen) to an interesting lecture yesterday.
5. When I (to enter) the classroom, the teacher (to write) words on the blackboard and the pupils (to copy) them into their exercise-books.
6. They (to get) ready to go out when it (to begin) raining.
7. Yesterday at one o'clock I (to have) lunch at the canteen.
8. When he (to come) in, I (to do) my exercises.
9. What you (to do) at eight o'clock yesterday?
10. At this time yesterday I (to go) home.
11. You (to sleep) when I (to go) out.
12. He (to read) on the sofa when I (to come) in and (to sit) down beside him.
13. I (to walk) along the street with my friend when a tram (to pass).
14. She (to look) out of the window when I (to see) her.
15. We (to answer) the teacher's questions when the headmistress (to enter) the classroom.