Page 151 - Advanced English Grammar in Use

K e i a t i v e c l a u s e s (Z) ( i o m , w n o i s o n i y s i x , c a n
s p e a k t h r e e l a n g u a g e s . )

Some relative clauses are used to add extra information about a noun, but this information is
not necessary to explain which person or thing we mean:
• Valerie Polkoff, who has died aged 90, escaped from Russia with her family in 1917.
• We received an offer of £80, 000 for the house, which we accepted.
These are sometimes called non-defining relative clauses. We don't use them often in everyday
speech, but they occur frequently in written English. Notice that we put a comma between the
Qnoun and a non-defining relative clause, and another comma at the end of this clause if it is not
•also the end of a sentence.
When we use a non-defining relative clause to add information about a person or people:
• we use who as the subject of the clause
• One of the people arrested
was Mary Arundel, who
is a member of the local council.
• we use who or whom as the object of the clause,
although whom is more formal and rarely
used in spoken English:
• Professor Johnson, who(m) I have long admired, is to visit the university next week.

When we use a non-defining relative clause to add information about a thing or group of things,
we use which as the subject or object of the clause:
• These drugs, which are used to treat stomach ulcers, have been withdrawn from sale.
• That Masters course, which I took in 1990, is no longer taught at the college.
That is sometimes used instead of which, but some people think this is incorrect, so it is
probably safer not to use it. We also use which to refer to the whole situation talked about in
the sentence outside the relative clause:
• The book won't be published until next year, which is disappointing.
• I have to go to hospital on Monday, which means I won't be able to see you.
We can also use whose in a non-defining relative clause (see also Unit 72):
• Neil Adams, whose parents are both teachers, won first prize in the competition.

•Notice that we don't use zero relative pronoun in a non-defining relative clause.

When we want to add information about the whole or a part of a particular number of things or
people we can use a non-defining relative clause with of which or of whom after words such as
all, both, each, many, most, neither, none, part, some, a number (one, two, etc.; the first, the
second, etc.; half, a third, etc.) and superlatives (the best, the biggest, etc.):
• The speed of growth of a plant is influenced by a number of factors, most of which we have
no control over.
• The bank was held up by a group of men, three of whom were said to be armed.
• The President has made many visits to Japan, the most recent of which began today.

We can use the following phrases at the beginning of a non-defining relative clause: at which
point/time, by which point/time, during which time, and in which case:
• It might snow this weekend, in which case we won't go to Wales.
• The bandages will be taken off a few days after the operation, at which point we will be able
to judge how effective the treatment has been.
• The next Olympics are in three years, by which time Stevens will be 34.

Relative clauses (1), (3) and (4)