Rewrite the following sentences by choosing the right word.

1. It's their / theirs problem, not our / ours.
2. This is a nice camera. Is it your / yours?
3. That's not my / mine umbrella. My / mine is black.
4. Whose books are these? Your / yours or my / mine?
5. Catherine is going out with her / hers friends this evening.
6. My / mine room is bigger than her / hers.
7. Can we use your washing machine? Our / ours is broken.