1.A 2.D 3.A 4.B 5.D 
II.
1. I sent my friend a letter in London last week.
→ A letter in London was sent to my friend last week by me
2. I last saw him when I was a student.
→ I haven’t seen him since I was a student
3. “Don’t forget to bring your passports with you when you go abroad.”
→ She reminded me to bring my passports with me when I went abroad
4. Smoking is not allowed in the ward.
→ Would you mind not smoking in the ward?
5. He failed the exam because of his laziness.
→ Because he was lazy, he failed the exam
III.
1.Instead of reusing plastic bags , we should use cloth bags.
2. Will you have a look at the house for me while I am on holiday?
3. We hope to give more green color to the town and earn some money for our group.
4. "Friends of the earth" is an organization protecting the planet.
5.  It was brave of him to jump into the river to save the child.