Choose the correct completion.

1. c
2. b
3. a
4. c
5. b
6. c
7. d
8. a
9. d
10. b
11. c
12. d
13. b
14. b
15. c
16. d
17. a
18. c
19. b
20. b


(Tư liệu tham khảo: Betty Schrampfer Azar. Understanding and Using English Grammar.3rd ed).

Review exercise