1. The old man is my grandfather. He lives next door.
-> The old man who lives next door is my grandfather.
2. Natalie is very friendly. She is a friend of Emma's.
-> Natalie, who is a friend of Emma, is very friendly.
3. Ve stayed at the Grand Hotel. Ann recommended it to us.
-> We stayed at the Grand Hotel, which Ann recommended to us.
4. The trousers are too small for me. I bought them yesterday.
-> The trousers which I bought yesterday ara too small for me.
5. John is one of my closest friends. I’ve known him for a very long time.
-> John, whom I've known for a very long time, is one of my closest friends.