Change the following sentences to PASSIVE VOICE

1. He is going to publish a new book.
   A new book .........
2. They haven't started the game yet.
   The game  yet.......
3. They could have broken the window.
   The window ......
4. Have they surprised you?
   Have ..........?
5. Where were they taking the taxis?
   Where ............?
6. We have to sign all the documents.
   All the documents ...........
7. Nobody can lift that stone.
   The stone ...........
8. Did they sign the contract?
   .................?
9. The student had cleaned the board before the teacher came in.
   The board .............. before the teacher came in.
10. They didn't return the books.
    The books .........
11. They are serving dinner now.
    Dinner ........... now.
12. The teacher punished the pupils.
    The pupils  ...........by the teacher.