I.
1. B
2. C
3. B
4. B
5. A
II.
6. C
7. C
8. A
9. B
10. A
III.
11. How old is your sister?
12. Hien is my new friend.
13. Do they like English?
14. How do you spell your name?
15. Are Linda and Tony your friends?
IV.
16. these -> this
17. he -> she
18. year -> years
19. is -> are
20. nine -> nice