1. Here is the book which is about Oliver Twist’s adventures.
2. A café is a small restaurant where people can get a light meal 
3. Summer is the time of year when the weather is the hottest 
4. The man, who was accused of having stolen a bike, will be sentenced to ten years’ imprisonment  
5. The man whom Cathy wanted to meet was away on holiday. 
6. I will have some repair the washing machine which my father bought two years ago.
7. The house which we are living in was built twenty years ago
8. The people whose house was damaged by the bomb will be compensated. 
9. We may never know the real reason why President Kennedy was assassinated 
10. Medical researchers have tested thousands of drugs on cancer victims, most of which prove to be useless.

1. Here is the book. It is about Oliver Twist’s adventures

Here is the book which is about Oliver Twist’s adventures.
2. A café is a small restaurant. People can get a light meal there.

A café is a small restaurant where people can get a light meal 

3. Summer is the time of year. The weather is the hottest then.
 Summer is the time of year when the weather is the hottest 

4. The man will be sentenced to ten years’ imprisonment. He was accused of having stolen a bike.
 The man, who was accused of having stolen a bike, will be sentenced to ten years’ imprisonment  

5. The man was away on holiday. Cathy wanted to meet him
 The man whom Cathy wanted to meet was away on holiday. 

6. I will have some repair the washing machine. My father bought it two years ago
 I will have some repair the washing machine which my father bought two years ago.

7. The house was built twenty years ago. We are living in the house.
 The house which we are living in was built twenty years ago

8. The people will be compensated. Their house was damaged by the bomb.
 The people whose house was damaged by the bomb will be compensated. 

9. We may never know the real reason. President Kennedy was assassinated for the reason.
 We may never know the real reason why President Kennedy was assassinated 

10. Medical researchers have tested thousands of drugs on cancer victims. Most of the drugs prove to be useless.

Medical researchers have tested thousands of drugs on cancer victims, most of which prove to be useless.