1. Mary don’t know whose sheet of paper it was.
2. We are talking about the book, which we bought a week ago.
3. I didn’t know the woman, who was looking at me yesterday in the shop.
4. Where is the cake, which he cooked yesterday?
5. Do you know whose dog it is?
6. I know who broke your laptop.
7. They are discussing the girl, who won the competition.
8. Do you see the cat, which has a big violet bow?
9. She wonders whose bike it is.
10. The chocolate which I bought is in the fridge
PS: whose - чей(отоносится к людям)
who - кто(про людей)
which - что(про неживие предметы или животных)