Answer:
7. Peter thought that his father left him behind but in fact he has not.
8. The teacher is sure that John didn't do his homework.
9. When they reached the station, they found that the train already left.
10. After the guests went we all lay down for a rest.
11. He talked to her as if he knew her for two years.
12. The teacher expected him to apologize because he misbehaved but he did not.