1. We can keep healthy by eating well and exercising regularly.
Correction: B. by eat (change "eat" to "eating")

2. It's easy to see that stamp collecting and coin collecting are parallel hobbies.
Correction: C. is (change "is" to "are")

3. We need calories to do things every day: walking, riding a bike, and even sleeping!
Correction: C. ride a bike (change "ride" to "riding")

4. Nancy loves cartoons, but she says she won't continue this hobby in the future.
Correction: C. she doesn't continue (change "doesn't continue" to "won't continue")

5. I didn't donate food but sang and danced with the elderly in the nursing home.
Correction: B. but sing (change "sing" to "sang")

6. Do you think having a healthy lifestyle is essential for all people?
Correction: No correction needed.

7. Don't eat too much ice cream because it can make you fat!
Correction: A. Don't to eat (remove "to")

8. Last year I encouraged her to work hard and to try for the examination.
Correction: A. encourage (change "encourage" to "encouraged")

9. My mum wants to keep fit, so she practices gym three times a week.
Correction: C. practises (change "practises" to "practices")

10. I asked some classmates about their hobbies and I got some interesting results.
Correction: C. get (change "get" to "got")