Here are the correct sentences in their PASSIVE FORMS.

1. Your last book was admired.
2. The door is being knocked at.
3. A car has been stolen.
4. We were bought sandwiches.
5. The exampapers are handed out.
6. You will be shown my house.
7. The lorry could be repaired.
8. The floor is being swept.
9. The law must be respected.
10. English is spoken all over the world.
11. He has been made a headmaster.
12. The bank was broken into.
13. I was sent a beautiful card.
14. All the exercises should be done.
15. My children are being looked after.
16. Your son was being told never to ride that bike.
17. The letter has been being typed.