1. They have just painted those posters

=> Those posters have just been painted.

2. The builders were building a new bridge

=> A new bridge was being built by the buiders.

3. Ba is preparing a reports now

=> A report was being prepared by Ba now.

4. Someone was making coffee when I came

=> The coffee was being made when I came.

5. No one has changed the room

=> The room hasn't been changed.

6. Are they mending your shoees at the moment?

=> Are your shoes being mended at the moment?

7. They haven't bought the flowers yet

=> The flowers haven't been bought yet.

8. People are laughing at him

=> He is being laughed at.
9. Some body was recording our conversation.

Our conversation was being recorded

10. We have seen her since last week

She has been seen by us since last week

11. Bill is using the computer at the moment

The computer is being used by Bill at the moment

12. Doctors have treated many people for burn

Many people have been treated for burn by doctors

13. People were watching the match on TV

The match on TV was being watched

14. Nobody has stolen his watch

His watch hasn't been stolen