English Grammar

Forms of the Relative Pronouns

Read the following sentences:

Here is a boy who is good at painting.
I know a man whose son lives abroad.
He is an actor whom many admire.

The relative pronoun who has three forms: who, whom and whose.

Who is used in the nominative case. It can be used to denote both singular and plural nouns. Whom is used in the objective case. Whose is used in the possessive case.

Which

This is the car which belongs to my grand father. (The relative pronoun which is the subject of the clause which belongs to my grand father.)
This is the car which I bought. (The relative pronoun which is the object of the clause which I bought.)

You will have noticed that which remains unchanged in the nominative (subject form) case and objective (object form) case. It has no possessive case.

That, what, as and but have the same form in all cases.