This is a town. I spent my childhood here.
This is the town WHERE I spent my childhood.
Sandra is the person. She dropped the plate on the floor.
Sandra is the person WHO dropped the plate on the floor.
The hotel clerk gave us our room keys. He speaks several languages.
The hotel clerk WHO gave us our room keys speaks several languages.
The professor is excellent. She lives in the city.
The professor, WHO is excellent, lives in the city.
The hybrid car helps him save gas. It is blue.
The hybrid car, WHICH helps him save gas. It is blue.
The city is very far. It is beautiful.
The city WHICH/THAT is very far is beautiful.
This is George. His brother went to school with me.
This is George whose brother went to school with me.
The classrooms were painted over the summer. They are blue and green.
The classrooms, WHICH/THAT were painted over the summer, are blue and green.
The author writes horror stories. Her book won he award.
The author, WHOSE book won the award, writes horror stories.
The pizza was very good. It was topped with pepperoni and sausage.
The pizza, WHICH was very good, was topped with pepperoni and sausage.