=>
III/
1. to play -> playing
2. used to singing -> used to sing
3. for -> by
4. to not -> not to
IV/
1. It's very important to keep the environment clean.
2. I haven't spoken to her for three years.
3. She told me not to forget to send my parents his regads.
4. Trung was given a microcomputer by his parents on his birthday.

5. D

6. B

7. C

8. D

1. D ⇒playing

2. C ⇒used to sing

3. C ⇒by

4. C ⇒not to

1. It's very important to keep the environmet clean.

2. I haven't spoken to her for three years.

3. She told me not to forget to send my parents her regards.

4. Trung was given a microcomputer by Trung's parents on his birthday.

                 

                             ~Chúc bạn học giỏi~