Transform these active sentences into passive sentences (don't write "by them"):
Respect the tenses and the affirmative, negative and interrogative form.
1. They open the windows every day. > The windows every day.
2. They don't turn the electricity off, in general. > The electricity off, in general.
3. Do they lock the door at night? > [?] at night?
4. They called Peter. > Peter .
5. They didn't close the doors. > The doors .
6. Did they stop the train? > ?
7. They will help Peter. > Peter .
8. If someone killed them, they would not reveal the secret. > If they , the secret [?].