Underline the mistake and correct it

Ex9: Underline the mistake and correct it.
1. When is he doing?
2. What is Anna doing? - He is reading books.
3. What are Mai and Hoa do?
4 . They're skating from the skate park
5. What are Linh and Hoa doing? She is singing at the studio
6. What is Peter's doing?
7. They're play video game at the arcade
8. She's is flying a kite at the park
9. The children a playing volleyball
10. I'm playing soccer at the soccer park