The boy___ is running is my brother.
WHO
I have a friend. He plays football.
I have a friend who plays football.
The man which is talking is my teacher.
WHO
The students who studied passed the test.
Defining
(Not all students—only those who studied)
My brother, who lives in London, is a doctor.
Non-defining
(I have only one brother → extra info about London)
The book ___ is on the table is mine.
WHICH/THAT
This is the house. It is very old.
This is the house which is very old.
The dog who is barking is loud.
WHICH/THAT
The book that I borrowed is interesting.
Defining
(We need “that I borrowed” to know which book)
This car, which is very old, still works.
Non-defining
(We already know which car → extra detail)
The girl ___ I met yesterday was nice.
WHO/THAT
I met a girl. You know her.
I met a girl who/that you know.
This is the place which I was born.
Prague, which is the capital of the Czech Republic, is beautiful.
Non-defining
(Prague is already clear → extra info)
The girl who is wearing a red dress is my sister.
Defining
(Identifies which girl)
This is the café ___ we had lunch.
WHERE
This is the movie. We watched it yesterday.
This is the movie that we watched yesterday.
My brother, who he lives in London, is 20.
remove HE
My teacher, who is very strict, gives a lot of homework.
Non-defining
(We know which teacher → description only)
The Eiffel Tower, which is in Paris, is famous.
Non-defining
(The object is unique → added information)
The man ___ car was stolen called the police.
WHOSE
That is the boy. His father is a doctor.
That is the boy whose father is a doctor.
The car, whose is new, is expensive.
WHICH
The people who live next door are very friendly.
Defining
(Specifies which people)
The car that he bought is very expensive.
Defining
(Without the clause, we don’t know which car)