Simple Past And Past Progresive

The simple past indicates that an activity or situation began and ended at a particular time in the past.
If a sentence contains when and has the simple past in both clauses, the action in the "when clause" happen first.
Example :
(a) I walked to school yesterday
(b) He lived in Paris for ten years, but now he is living on Rome
(c) When I dropped my cup, the coffee spilled my lap
(d) I stood under a tree when it began to rain

- Exercise -

1. Gene was eating (eat) dinner when his friend called.
2. While Maria was cleaning the apartement, her husband was sleeping (sleep).
3. At three o'clock this morning, Eleanor was studying (study).
4. When Mark arrived, the Johnsons were having (have) dinner, but they stopped in order to talk to him.
5. John went (go) to France last year.
6. When the teacher entered (enter) the room, the students were talking.
7. While Joan was writing the report, Henry was looking (look) for more information.
8. We saw (see) this movie last night.
9. At one time, Mr.Roberts was own this building.
10. Jose was writing (write) a letter to his family when his pencil broke (break).