1. Thomas Edison invented the electric light bulb. → The electric bulb was invented by Thomas Edison.

2. A stranger helped him. → They were helped by a stranger.

3. Someone painted the house last week. → The house was painted by someone last week.

4. Some children saw the accident yesterday. → The accident was seen by some children at school.

5. Where do they make these caps? → Where are these caps made?

6. Several countries signed the contract. → The contact was signed by several countries.

7. I don't send emails at weekends. → Emails aren't send on weekends.