1. watches (seldom -> HTĐ)
2. learns (always -> HTĐ)
3. does...begin (Có lịch trình -> HTĐ)
4. boils - freezes (Sự thật hiển nhiên -> HTĐ)
5. bought (ago -> QKĐ)
6. travelled (In the past -> QKĐ)
7. was - played (Đã xảy ra, đã kết thúc -> QKĐ)
8. Did you go (last Sun -> QKĐ)
9. don't use - type (Sự thật -> HTĐ)
10. works - travels (Đang xảy ra -> HTĐ)
11. attacked (Sep 11th, 2001 -> QKĐ)
12. didn't attend - forgot (last Tues -> QKĐ)
13. didn't watch - went (last night -> QKĐ)
14. did you graduate (Đã xảy ra, đã kết thúc -> QKĐ)
15. used - was (Yesterday -> QKĐ)
16. taught (lasst semester -> QKĐ)