1. Mary types letters in the office.
=> Letters is typed in the office by Mary.
2. His father will help you tomorrow.
=> You will be helped by his father tomorrow.
3. Science and technology have completely changed human life
=> Human life were completely changed by science and technology/
4. Peter broke this bottle.
=> This bottle is broken by Peter.
5. They are learning English in the room.
=> English are being learnt in the room.
6. Nothing can change my mind.
=> My mind can't be changed.
7. No one had told me about it.
=> I hadn't been told about it.
8. I don’t know her telephone number
=> Her telephone number isn't known by me.
9. My students will bring the children home.
=> The children home will be brought by my students.
10. They sent me a present last week.
=> A present was sent me last week.