Here are the mistakes in each sentence along with their corrections:

26. **Surfing the net is most exciting than cooking meals.**
- **Correction:** "is more exciting than"

27. **Using too much computer is harmful because it can hurts your eyes.**
- **Correction:** "can hurt"

28. **I was interested in chatting with friends in my free time everyday.**
- **Correction:** "every day" (as two words)

29. **Mai usually hang out with her friends in the evenings.**
- **Correction:** "hangs out"

30. **We find making origami is really interesting.**
- **Correction:** "find making origami really interesting."

Feel free to ask if you need more help!