Unit 8
Lesson 2
Student’s Book page 63
GRAMMAR
GRAMMAR: Non-defining relative clauses
Non-defining relative clauses
● Non-defining relative clauses are used to give more detail about a particular person, place or thing that is being talked about. The non-defining relative clause (underlined in the examples below) is usually connected to the main clause by a relative pronoun such as who, which, where or when.
We use:
-who to refer to people;
-which to refer to things and animals;
-where to refer to places
-when to times.
-Whose is the possessive form of who.
-Geologists, who study Earth’s rocks and how they formed, can ‘read’ layers of rock.
-In the Antarctic, where plants and animals face a harsh cold environment, archaeologists have found evidence that this area was once much warmer.
-Humans, whose activities cause global warming, need to take action.
-The Sahara desert, which is in Africa, is very hot.
-Several ice ages, when glaciers covered much of Earth's surface, have taken place.
● A non-defining relative clause differs from a defining relative clause in that it gives additional, rather than essential, information and, without it, the sentence would still convey meaning.
-Geologists can ‘read’ layers of rock. In the Antarctic, archaeologists have found evidence that this area was once much warmer.
● Non-defining relative clauses follow a noun and are enclosed between two commas (or dashes or brackets), unless completing the sentence.
-Archaeologists have found fossils of trees in parts of Antarctica, which prove that this area was much warmer 110 million years ago than it is today.
● In non-defining relative clauses, the relative pronoun is never omitted.