14 D

15 B

16 A

II

1 If it hadn't rained heavily yesterday, they would have played football.

2 If Lan knew his number, she would phoned him.

3 If they invited me to their birthday paties, I could come there.

4 If she had had your adress, she could gone to your home.

5 If Tom had worked hard, he would have passed the first examination.

6 If we didn't have to go to school everyday, we would visited Ha Long Bay with the form teacher.

7 This problem can be solved by no one.

8 This machine mustn't be used after 5:30 pm.

9 While she was reading newspaper, I came.

10 His homework is being done by him at the moment.

`~rai~`

$\begin{array}{I}\text{1.If it hadn't rainned heavily,they would have played football.}\\\text{2.If Lan knew his number,she would call him.}\\\text{3.If they invited me to their birthday,I could come.}\\\text{4.If she had had your address,she could have gone to your house.}\\\text{5.If Tom had worked hard,he wouldn't have failed the first examination.}\\\text{6.If we didn't have to go to school every day,we would visit Ha Long Bay with the form teacher.}\\\text{18.This problem can't be solved.}\\\text{19.This machine mustn't be used after 5.30 o'clock.}\\\text{20.When I came,the newspaper was being read by her.}\\\text{21.His homework is being done at the moment.}\end{array}$