1. When I came they were watching television.
2. He had written his letter by 10 o'clock yesterday.
3. After he had read the book, he wrote a composition.
4. He was eating a sandwich when we saw him.
5. What had you done by 5 o'clock last night?
6. Where did he go to tomorrow?
7. Who was singing when you came?
8. Has he been your friend since childhood.