Answer:
1. Sarah could play the piano when she was a kid. Now, she can't.
2. It's sunny and warm today. It might not rain.
3. Can I open the window? It's boiling hot in here.
4. The doctor advised me that shouldn't eat junk food.
5. We have to leave now. If we don't we'll miss our flight.
6. I don't have to get up early tomorrow. There's no class.
7. Employees must wash their hands before working.
8. I don't like my job. I think I should quit it.