Answer:
When, then, as soon as, before, etc.
Explanation:
1. He felt much better when he had solved the problem.
2. The weeks went by and then I started to feel better.
3. He put down his suitcase for a minute and then he picked it up again and walked on.
4. When I phoned my sister, she was having a shower.
5. As soon as you get there, please phone and let me know.
6. I used my dictionary a lot before but now I try to guess what the words mean.
7. As soon as I got home, I found my friends had arrived.
8. While you were sleeping, something really interesting happened.