Sure, I'll help you identify the incorrect words or phrases in each sentence.

1. Tim is at the same age as Hoa.
- Incorrect: **at** (It should be "the same age as" without "at")

2. At recess, the students practice to play basketball.
- Incorrect: **to play** (It should be "practice playing")

3. Do you know how much a banana cost?
- Incorrect: **cost** (It should be "costs")

4. The teacher says Ba will be a famous artist in one day.
- Incorrect: **in one day** (It should be "one day")

5. Some boys are playing marble in the school yard at recess.
- Incorrect: **marble** (It should be "marbles")

6. Some students are playing games as blind man’s buff and catch.
- Incorrect: **as** (It should be "like")

7. Mai learns how to use a computer in her scientific class.
- Incorrect: **scientific** (It should be "science")

8. I’d love coming to your birthday but I’m much too busy.
- Incorrect: **coming** (It should be "to come")

9. There are less TV programs for teenagers than there are for adults.
- Incorrect: **less** (It should be "fewer")

10. People are living longer so there are more and more many old people.
- Incorrect: **many** (It should be "more")