Relative clauses: Defining and non-defining

Defining vs non-defining

There are two types of relative clauses: defining and non-defining. In the grammar chart below, you can see the main differences between them.

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Relative pronouns

Relative pronouns are the words that introduce relative clauses. They can act as the subject or the object of the relative clause.

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❗ Note that that can be used in informal English instead of who/whom/which, but it is never used after a comma (in non-defining relative clauses) or after a preposition.

• That’s the man who/that offered me the job.
• My mother’s older brother, who (that ) lives in New York, is coming to visit.
• That’s the house in which (that ) they lived all their lives.

Which/that vs What

We use which/that as relative pronouns. They refer back to a noun or sentence.

• I gave her the letter which/that I had been keeping since the war. (which/that= the letter)
• He offered to help us, which was a nice gesture. (which= He offered to help us)

We don’t use what as a relative pronoun. It cannot be used to refer back to a sentence or noun.

• I gave her the letter which/that I had been keeping since the war.
• I gave her the letter what I had been keeping since the war.
• He offered to help us, which was a nice gesture.
• He offered to help us, what was a nice gesture.

We use what independently to mean ‘the thing/s that’.

• I didn’t like what he did.= I didn’t like the thing/s that he did.
• What I don’t understand is why we are here. (what= the thing that)

Prepositions in relative clauses

When the relative pronoun is the complement of a preposition, we can use the preposition before the relative pronoun or at the end of the relative clause.

Preposition + relative pronoun

It’s not very common to use prepositions before relative pronouns, we just do it in formal language.

• He wrecked the car for which he had paid a fortune.
• He was a man for whom everybody had great respect.  

❗ Note that after a preposition, we can only use the pronouns whom or which. (NOT who or that).

We can also use whose after a preposition.

• The team signed then the young Maradona, in whose skills everybody had their hopes.

Preposition at the end of the relative clause

The most common position of the preposition is at the end of the relative clause.

• He wrecked the car for which he had paid a fortune. (Formal; not common in spoken English)
• He wrecked the car (which/that) he had paid a fortune for. (Informal)

Relative adverbs

Relative adverbs introduce relative clauses, just like relative pronouns, but in this case, they are used to introduce information about time (when), place (where), or reason (why).

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❗ Note that we can use a preposition + which instead of a relative adverb. However, this structure is more formal and not as common.

• The coach changed the time when the players had to get up. 
• =The coach changed the time at which the players had to get up.
• The bench where they were sitting was dirty.
• =The bench on which they were seated was dirty.

Quantifier + of which/whom

In non-defining relative clauses (=between commas), we can use of which/whom after a quantifier such as some, any, none, all, both, several, enough, many and few. 

• Their daughters, both of whom are in university, don’t visit them very often. 
• The students, none of whom had failed the exam, were thrilled. 
• Their house was full of cats, most of which had been found in the street. 
• The two rooms, neither of which had windows, were small and dirty. 

We can also use a quantifier + of whose.

• I belong to a reading club, most of whose members are retired teachers. 
• The parents, some of whose children were already grown-ups, marched down the street.