1. Letters are typed in the office by Mary

2. You will be helped by his father tomorrow

3. Human life has completely changed by science and technology 

4. This bottle was broken by Peter 

5. English is being learnt in the room

6. My mind can't be changed 

7. I hadn't been told about it

8. Her telephone number isn't known by me

9. The children will be brought home by my students 

10. I was sent a present last week

     A present was sent me last week

11. We were given more information by her

12. All the workers of the plan were being instructed by the chief engineer 

13. Tea can't made with cold water

15. The meeting will be held before May Day

QKĐ: S + was/ were + PP + (by O)

HTĐ: S + am/ is/ are + PP + (by O)

HTTD: S + am/ is/ are + being + PP + (by O)

HTHT: S + have/ has + been + PP+ (by O)

TLĐ: S + will be + PP + (by O)

TLG: S + is/ am/ are + going to + be + PP + (by O)

S + modal verb (should, must, have to, can,...) + be + PP + (by O)