Level: beginner

The relative pronouns are:

Subject	Object	Possessive
who	who/whom	whose
which	which	whose
that	that	–

We use relative pronouns to introduce relative clauses. Relative clauses tell us more about people and things:

Lord Thompson, who is 76, has just retired.
This is the house which Jack built.
Marie Curie is the woman that discovered radium.

We use:

• who and whom for people
• which for things
• that for people or things.

Two kinds of relative clause

There are two kinds of relative clause:

1.  We use relative clauses to make clear which person or thing we are talking about:

Marie Curie is the woman who discovered radium.
This is the house which Jack built.

In this kind of relative clause, we can use that instead of who or which:

Marie Curie is the woman that discovered radium.
This is the house that Jack built.

We can leave out the pronoun if it is the object of the relative clause:

This is the house that Jack built. (that is the object of built)

Be careful!
The relative pronoun is the subject/object of the relative clause, so we do not repeat the subject/object:Marie Curie is the woman who she discovered radium. (who is the subject of discovered, so we don’t need she)This is the house that Jack built it. (that is the object of built, so we don’t need it)

2.  We also use relative clauses to give more information about a person, thing or situation:

Lord Thompson, who is 76, has just retired.
We had fish and chips, which I always enjoy.
I met Rebecca in town yesterday, which was a nice surprise.

With this kind of relative clause, we use commas (,) to separate it from the rest of the sentence.

Be careful!
In this kind of relative clause, we cannot use that: Lord Thompson, who is 76, has just retired. (NOT Lord Thompson, that is 76, has just retired.)and we cannot leave out the pronoun: We had fish and chips, which I always enjoy. (NOT We had fish and chips, I always enjoy.)

Level: intermediate

whose and whom

We use whose as the possessive form of who:

This is George, whose brother went to school with me.

We sometimes use whom as the object of a verb or preposition:

This is George, whom you met at our house last year.
(whom is the object of met)

This is George’s brother, with whom I went to school.
(whom is the object of with)

but nowadays we normally use who:

This is George, who you met at our house last year.
This is George’s brother, who I went to school with.

Relative pronouns with prepositions

When who(m) or which have a preposition, the preposition can come at the beginning of the clause:

I had an uncle in Germany, from who(m) I inherited a bit of money.
We bought a chainsaw, with which we cut up all the wood.

or at the end of the clause:

I had an uncle in Germany, who(m) I inherited a bit of money from.
We bought a chainsaw, which we cut all the wood up with.

But when that has a preposition, the preposition always comes at the end:

I didn’t know the uncle that I inherited the money from.
We can’t find the chainsaw that we cut all the wood up with.

when and where

We can use when with times and where with places to make it clear which time or place we are talking about:

England won the World Cup in 1966. It was the year when we got married.
I remember my twentieth birthday. It was the day when the tsunami happened.

Do you remember the place where we caught the train?
Stratford-upon-Avon is the town where Shakespeare was born.

We can leave out when:

England won the World Cup in 1966. It was the year we got married.
I remember my twentieth birthday. It was the day the tsunami happened.

We often use quantifiers and numbers with relative pronouns: 

all of which/whom	most of which/whom	many of which/whom
lots of which/whom	a few of which/whom	none of which/whom
one of which/whom	two of which/whom	etc.

She has three brothers, two of whom are in the army.
I read three books last week, one of which I really enjoyed.
There were some good programmes on the radio, none of which I listened to.