Collins Cobuild

Unit 93
Non-defining clauses
Main points
You  use  non-defining  relative  clauses  to  give  extra  information
about the person or thing you are talking about.
Non-defining  relative  clauses  must  be  introduced  by  a  relative
pronoun such as ‘which’, ‘who’, ‘whom’, or ‘whose’.
A non-defining relative clause comes immediately after a noun and
needs a main clause to make a complete sentence.
1
You use non-defining relative clauses to give extra information about
the  person  or  thing  you  are  talking  about.  The  information  is  not
needed to identify that person or thing.
Professor Marvin, who was always early, was there already.
‘Who  was  always  early’  gives  extra  information  about  Professor
Marvin. This is a non-defining relative clause, because it is not needed
to  identify  the  person  you  are  talking  about.  We  already  know  that
you are talking about Professor Marvin.
Note that in written English, a non-defining relative clause is usually
separated from the main clause by a comma, or by two commas.
I went to the cinema with Mary, who you met.
British Rail, which has launched an enquiry, said one coach was badly

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damaged.
2
 You  always  start  a  non-defining  relative  clause  with  a  relative
pronoun. When you are talking about people, you use ‘who’. ‘Who’ can
be the subject or object of a non-defining relative clause.
Heath Robinson, who died in 1944, was a graphic artist and
cartoonist.
I was in the same group as Janice, who I like a lot.
In formal English, ‘whom’ is sometimes used instead of ‘who’ as the
object of a non-defining relative clause.
She was engaged to a sailor, whom she had met at Dartmouth.
3
When you are talking about things, you use ‘which’ as the subject or
object of a non-defining relative clause.
I am teaching at the Selly Oak centre, which is just over the road.
He was a man of considerable inherited wealth, which he ultimately
spent on his experiments.
WARNING: You do not normally use ‘that’ in non-defining relative
clauses.
4
You can also use a non-defining relative clause beginning with ‘which’
to say something about the whole situation described in a main clause.
I never met Brando again, which was a pity.
She was a little tense, which was understandable. Small computers
need only small amounts of power, which means that they will run on
small batteries.
5
When you are talking about a group of people or things and then want
to  say  something  about  only  some  of  them,  you  can  use  one  of  the
following expressions:
many of which
many of whom

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none of which
none of whom
one of which
one of whom
some of which
some of whom
They were all friends, many of whom had known each other for years.
He talked about several very interesting people, some of whom he was
still in contact with.
6
You can use ‘when’ and ‘where’ in non-defining relative clauses after
expressions of time or place.
This happened in 1957, when I was still a baby.
She has just come back from a holiday in Crete, where Alex and I
went last year.

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