1. She was busy.
2. I wasn't busy.
3. Were you busy?
4. Were they at home?
5. He wasn't at home.
6. I didn't know.
7. Did they know?
8. She didn't know.
9. Who did know?
10. Nobody didn't know.
11. Did he read English books?
12. They have never read.
13. Did she have a flat?
14. He didn't have anything.
15. Who it was?