1. Thank you for your letter, which I was very happy to get.
2. Who was that girl with whom you talked in the party last night.
3. Her son, who went to the same school with me, was very intelligent.
4. I want to see the man who had phoned me.
5. Our teacher, who is an American, naturally speaks English perfectly.
6. The car which John used belongs to his uncle.
7. This machine, which I have used for twenty years, is still working perfectly.
8. The boy is with him is his son.
9. This is a kind of exercise which I like best.
10. The man who answered the phoned said Tom was out.
11. The bed on which I sleep has no mattress.
12. Don't sit on the chair whose leg is broken.
13. That was the time when he managed the enterprise.
14. I never forget the park where we first met.
15. They gave me four bad tyres, one of which was from abroad.