Change the active into passive voice

1. Chalk is used for writing on the blackboard.
2. This hospital was built two years ago.
3. The cake was eaten by them.
4. Where a new school will be built?
5. The telegram had been sent before his brother returned.
6. His novels are read all over the world.
7. This consonant is pronounced with aspiration.
8. The light wasn't turned off.
9. This work will be finished in time.
10. The door has been left open.
11. The book will have been read by then.
12. Are oranges being sold?