1. Mary types letters in the office.

=> Letters are typed in the office by Mary.
2. His father will help you tomorrow.

=> You’ll be helped by his father tomorrow.

3. Science and technology have completely changed human life.

=> The human life has completely been changed with science and technology.

4. Peter broke this bottle.

=> This bottle was broken by Peter.

5. They are learning English in the room.

=> English is 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.

9. My students will bring the children home.

=> The children will be brought home by my students.
10. They sent me a present last week.

=> I was sent a present last week.

11. She gave us more information.

=> We were given more information.

12. The chief engineer was instructing all the workers of the plan.

=> All the workers of the plan were being instructed by the chief engineer.
13. They can’t make tea with cold water.

=> Tea can’t be made with cold water.

14. Somebody has taken some of my books away.

=> Some of my books have been taken away.
15. They will hold the meeting before May Day.

=> The meeting will be held before May Day.