Role of an adjective (they refer to a noun/pronoun in the main clause). Compare: I’d like to buy a large

Relative clauses – introduction

Relative Clauses are subordinate clauses which start with a relative pronoun (eg. who, which or that) and play the role of an adjective (they refer to a noun/pronoun in the main clause). Compare:

I’d like to buy a large house.

I’d like to buy a house that would be large enough for our family.

Relative pronouns and adverbs used: who/that/whom (formal) – for people

which/ that – things

whose – possession

where – place

when – time

why – reason
When and where are used in the same way as preposition+which:
I’ll never forget the day when I first met you. (… the day on which …)

Do you know a shop where I can find sandals? (… a shop at which …)

Why is used in a similar way after reason:
Do you know the reason why she doesn’t like me? (… the reason for which …)
Whose can refer back to people or things and is used for POSSESSION:
I saw a girl whose beauty took my breath away.

It was a meeting whose purpose I did not understand.

Instead of whose we can use other structures:
He’s written a book whose name I’ve forgotten.

He’s written a book the name of which I’ve forgotten. (the most common word order)

He’s written a book that I’ve forgotten the name of. (the most common word order, less formal)

He’s written a book of which I’ve forgotten the name. (also possible)

THAT

We often use that instead of who or which, especially in an informal style:

I like people that smile a lot.

This is the key that opens the garage.