A lion is an animal. It is very strong.
A lion is an animal which/that is very strong.
A detective is someone. He discovered the truth about crimes.
A detective is someone who/that discovers the truth about crimes.
Marie Curie is the woman. She discovered radium.
Marie Curie is the woman who/that discovered radium.
The money is in the kitchen. The money belongs to John.
The money that / which belongs to John is in the kitchen.
They live in a city. The city is in the North of England.
They live in a city that is in the North of England.
She worked for a man. The man used to be an athlete.
She worked for a man who used to be an athlete.
The woman drove the car. She was nervous.
The woman who drove the car was nervous.
