answer : 

1. The first man set a good example.

2. The students are well-prepared to take the exam.

3. It took me hours to download the file.

4. I’m starving. I need to eat something.

5. I’m a boss. I used to tell people what to do.

6. He was made to sign the contract.

7. I didn’t know how to get there.

8. Most of the teachers don’t allow their students to talk during class.

9. It’s important to start early.

10. There are too many people here for me to talk to.

11. You usually need flour, salt, and yeast to make bread.

12. I’d rather listen to friends, but being alone is also enjoyable.

13. She sent me an e-mail to inform me of the update.

14. Elvis was more popular than the Beatles were.

15. He told me that the meeting had been canceled. (This sentence is already correct.)