1. They repaired the piano yesterday.
`→` The piano was repaired yesterday.
2. What a pity! They don't go to the party.
`→` They wish they went to the party.
3. '' Where are you staying now? ''
`→` He asked me where I was staying then.
4. She had to stay at home because the weather was cold.
`→` Because of the cold weather, so he had to stay at home.