Make the sentences passive

1. The butter is kept in the fridge.
2. The bridge was repaired.
3. The truth should be told him.
4. The doors must be shut.
5. I was invited to the party.
6. I was taken to the zoo.
7. Their house will be sold.
8. This picture was painted by Picasso.
9. He must be written to.
10. The old newspapers were thrown away.
11. The children were looked after well.
12. The cat can be played with quite safely.