1. He didn’t know WHOSE sheet of paper it was. 2. We are talking about the book WHICH we bought yesterday. 3. I don’t know the man WHO is looking at me. 4. Where is the pizza WHICH she cooked yesterday? 5. Do you know WHOSE cat it is? 6. I know WHO broke your smartphone. 7. We are discussing the boy WHO won the competition. 8. Do you see the elephant WHICH has a big red bow? 9. He wonders WHOSE house it is. 10. The apple-pie WHICH I bought is in the fridge.