1. Letters are typed in the office by Mary.
2. You will be helped by his father tomorrow.
3. Human life has been completely changed by Science and Technology.
4. This bottle was broken by Peter.
5. English is being learned in the room.
6. My mind can be changed by nothing.
7. I had been told about it by no one.
8. Her telephone isn't known.
9. The children will be brought home by my students.
10. A present was sent to me last week.
