C- Change into the past. 1. He is a good student.
2. They are here.
3. It's all right.
4. We are busy.
5. She is happy.
6. They are at school.
7. I'm not in the garden.
8. They aren't sad.
9. Where is he?
10. Isn't he at home?
11. It isn't important.
12. Is the lesson difficult?
13. Who are they?
14. Are the windows open?