1. The bird isn't singing (-)
2. Is the bird singing? (?)
3. We aren't playing in the park (-)
4. Are we playing in the park? (?)
5. I'm not reading a book (-)
6. Am I reading a book? (?)
7. They aren't sitting near the window (-)
8. Are they sitting near the window? (?)
9. Ann isn't writing an exercise (-)
10. Is Ann writing an exercise? (?)