We like skating / we don't like skating.
My sister works at the hospital / My sister doesn't work at the hospital.
My friend is a student / My friend isn't a student
1. I am writing
2. I was writing
3. is sleeping
4. was sleeping
5. are not doing
6. were not doing
7. Are you eating ice-cream now?
8. Were you eating ice-cream...?
9. What is your father doing now?
10. What was your father doing...?
11. Why is she crying now?
12. Why was she crying...?
13. She was reading...
14. is not reading
15. is going
16. What are you doing now? - I am drinking tea.
17. Were you drinking tea at this time yesterday? - No, I was not drinking tea at this time yesterday, I was eating a banana.
18. was reding, is reading
19. is playing
20. was shining, were singing