1. 主动语态：We use electricity to run machines.
被动语态：Electricity is used to run machines.
2. 主动语态：Bell invented the telephone in 1876.
被动语态：The telephone was invented by Bell in 1876.
3. 主动语态：She steals my bike.
被动语态：My bike is stolen by her.
4. 主动语态：He answers the questions in public.
被动语态：The questions were answered in public.
5. 主动语态：They are repairing the bridge.
被动语态：The bridge is being repaired by them.
6. 主动语态：A schoolboy found this wallet in the street.
被动语态：This wallet was found in the street by a schoolboy.
7. 主动语态：Lucy bought some fruit.
被动语态：Some fruit was bought by Lucy.
8. 主动语态：Uncle Wang waters the flowers every day.
被动语态：The flowers are watered by Uncle Wang every day.
9. 主动语态：They built the bridge in 1998.
被动语态：The bridge was built by them in 1998.
10. 主动语态：Tom wrote a letter to his friend.
被动语态：A letter was written to his friend by Tom.