I)
1. came -> come
2. it -> them
3. go last -> last go
4. to -> in
II)
1. amazed
2. pollution
3. friendship
4. impressing
III)
1. If he had hurried, he wouldn't have missed the train
2. I prefer to listen to music to play football
3. He told me not to put off my work until the following day
4. Two department stores have been built this year
5. People use computers to design new models
6. My boss asked me if I could speak English
7. If they took a map, they couldn't lose the way.