1. They didn't allow Tom to take these books home.
=>Tom wasn't allowed to take these books home
2. How many trees did they cut down to build that fence?
=>How many trees were cut down to build that fence?
3. This well-know library attracts many people.
=>Many people are attracted by this well-known library
4. People say that he is intelligent.
=>He is said to be intelligent
5. This is the second time they have written to us about this.
=>This is the second time we have been written to about this
6. They didn't look after the children properly.
=>The children weren't looked after properly