21, D – on

22, A – Biology

23, D – Twice a week

24, C – semesters

25, A – dictionary

26, A – An hour

27, C – result

28, C- for

29, A – on

30, C – conversation

IX

1, Mai told them to correct the mistakes.

2, Lan asked me if I could carry her suitcase.

3, Tom told the children not to play video games too much.

4, Mr. White said that Tim should practice English every day.

5, Phong studies carefully.

6, Nga told me if I could take her to the bank.

7, Mr. Hung asked them not to talk in class.

8, Miss. Lan said that I shouldn’t smoke cigarette.

9, Mai always studies well.

10, Mai and Lan always play tennis skillfully.