I.
1. I told a joke but nobody laughed.
2. You must study harder or you will go into another class.
3. The city suffers from air pollution and the city suffers from water pollution.
4. I knew her family so I did what I could for her.
5. We can't affore energy-saving light bulbs because the light bulbs are too expensive.
II.
1. learnt
2. don't have
3. attend
4. will die
5. doesn't have
6. wasn't
7. will clean
8. wasn't
III.
1. for
2. on
3. for
4. off
5. on
6. away
7. in
8. up
Chúc bạn học tốt :3