We can use sentences to describe nouns. To join sentences to nouns, we use relative pronouns.
Relative pronouns are "who, which and that".
We use "who" for people, "which" for things and "that" for people and things.
The dictionary isn’t very good. I bought it yesterday.
The dictionary which I bought yesterday isn’t very good.
We use “who” or “which” instead of “he, him, she, it, etc.” We don’t use both.
The man is a doctor. He lives downstairs.
The man who lives downstairs is a doctor.
We can use “whom” for people when relative pronoun is the object of the following verb. But it is formal and unusual.
I have just got an email from the woman whom I met on holiday last year.
When a relative pronoun (who, which, that) is the object of a following verb, we can leave it out. But if a relative pronoun is a subject of the following verb, we can’t leave it out.
The man that I phoned spoke Turkish. or The man I phoned spoke Turkish.
The man that spoke Turkish is my friend. We cannot say; The man spoke Turkish is my friend.
• People who are clever can always find a way.
• This is the bank which was robbed yesterday.
• A boy who is in my class was in the bank at that time.
• The man who robbed the bank had two pistols.
• He wore a mask which made him look like Mickey Mouse.
• He came with a friend who waited outside in the car.
• The woman who gave him the money was young.
• The bag which contained the money was yellow.