5. Find the mistakes.

Here are the corrections for the sentences:

1. They **are** going to school.
2. Helen is reading a book. (Correct)
3. My friends and I **are** skating.
4. I **am** dreaming.
5. We **are writing** a composition.
6. They are **taking** a photo.
7. Jack and Tim **are** playing chess.
8. My sister **is feeding** a pet.
9. David **is doing** his homework.
10. I am walking my dog. (Correct)
11. We are **smiling**.