Ngữ pháp Tiếng Anh Lớp 6 - Relative clauses

RELATIVE CLAUSES
NON-DEFINING RELATIVE CLAUSES
The information in these clauses is not essential. It tells us more about someone or something, but it does not help us to identify them or it. 
Compare:
1. Elephants that love mice are very unusual. (This tells us which elephants we are talking about).
2. Elephants, which are large and grey, can sometimes be found in zoos. (This gives us some extra information about elephants - we are talking about all elephants, not just one type or group).
3. John's mother, who lives in Scotland, has 6 grandchildren. (We know who John's mother is, and he only has one. The important information is the number of grandchildren, but the fact that she lives in Scotland might be followed with the words "by the way" - it is additional information). 
Punctuation
Non-defining relative clauses are always separated from the rest of the sentence by commas. The commas have a similar function to brackets:
My friend John has just written a best-selling novel. (He went to the same school as me) > My friend John, who went to the same school as me, has just written a best-selling novel. 
Relative pronouns in non-defining clauses
Person 
Thing 
Place 
Subject 
who 
which 
Object 
who/whom 
which 
where 
Possessive 
whose 
Notes: 
1. In non-defining clauses, you cannot use ‘that’ instead of who, whom or which.
2. You cannot leave out the relative pronoun, even when it is the object of the verb in the relative clause:
He gave me the letter, which was in a blue envelope.
He gave me the letter, which I read immediately
3. The preposition in these clauses can go at the end of the clause, e.g. This is Stratford-on-Avon, which you have all heard about.
This pattern is often used in spoken English, but in written or formal English you can also put the preposition before the pronoun: e.g. Stratford-on-Avon, about which many people have written is Shakespeare’s birthplace.
4. Non-defining clauses can be introduced by expressions like all of, many of + relative pronoun: 
Person
Thing
all of
+ whom
+ which
any of
+ whom
+ which
(a) few of
+ whom
+ which
both of
+ whom
+ which
each of
+ whom
+ which
either of
+ whom
+ which
half of
+ whom
+ which
many of
+ whom
+ which
most of
+ whom
+ which
much of
+ whom
+ which
none of
+ whom
+ which
one of
+ whom
+ which
two of etc 
+ whom
+ which
Examples:
a. There were a lot of people at the party, many of whom I had known for years.
b. He was carrying his belongings, many of which were broken. 
5. The relative pronoun which at the beginning of a non-defining relative clause, can refer to all the information contained in the previous part of the sentence, rather than to just one word.
a. Chris did really well in his exams, which was a big surprise. (= the fact that he did well in his exams was a big surprise).
b. An elephant and a mouse fell in love, which is most unusual. (= the fact that they fell in love is unusual).
Examples: 
a. My grandmother, who is dead now, came from the North of England.
b. I spoke to Fred, who explained the problem.
c. The elephant looked at the tree, under which she had often sat.
d. We stopped at the museum, which we’d never been into.
e. She’s studying maths, which many people hate.
f. I’ve just met Susan, whose husband works in London.
g. He had thousands of books, most of which he had read.
RELATIVE CLAUSES
DEFINING RELATIVE CLAUSES 
As the name suggests, these clauses give essential information to define or identify the person or thing we are talking about. Obviously, this is only necessary if there is more than one person or thing involved.
Example:
Elephants who marry mice are very unusual.
In this sentence we understand that there are many elephants, but it is clear that we are only talking the ones who marry mice.
Punctuation
Commas are not used in defining relative clauses.
Relative pronouns
The following relative pronouns are used in defining relative clauses: 
Person 
Thing 
Place 
Time 
Reason 
Subject 
who/that 
which/that 
Object 
who/whom/that/ø 
which/that/ø 
where 
when 
why 
Possessive 
whose 
whose 
Notes:
1. The relative pronoun stands in place of a noun.
This noun usually appears earlier in the sentence:
The woman 
who/that 
spoke at the meeting 
was very knowledgeable. 
Noun, subject of
main clause 
relative pronoun referring to 'the woman', subject of 'spoke' 
verb + rest of relative clause 
verb + rest of main clause 
2. Who, whom and which can be replaced by that. This is very common in spoken English.
3. The relative pronoun can be omitted (ø) when it is the object of the clause:
The mouse that the elephant loved was very beautiful.
OR The mouse the elephant loved was very beautiful.
Both of these sentences are correct, though the second one is more common in spoken English.
The mouse 
that/ø 
the elephant loved 
was very beautiful. 
Noun, subject of main clause 
relative pronoun, referring to 'the mouse, object of 'loved' 
verb + rest of relative clause 
verb + rest of main clause. 
(You can usually decide whether a relative pronoun is an object because it is normally followed by another subject + verb.)
4. Whose is used for things as well as for people.
Examples:
The man whose car was stolen.
A tree whose leaves have fallen.
5. Whom is very formal and is only used in written English. You can use who/that, or omit the pronoun completely :
The doctor whom/who/that/ø I was hoping to see wasn't on duty.
6. That normally follows words like something, anything, everything, nothing, all, and superlatives.
Examples:
There's something that you should know. 
It was the best film that I've ever seen. 
Examples:
A clown is someone who makes you laugh. 
An elephant is an animal that lives in hot countries. 
The plums that were in the fridge were delicious. I have eaten them. 
Where are the plums (that) I put in the fridge? 
Has anyone seen the book I was reading? 
Nothing that anyone does can replace my lost bag. 
Let's go to a country where the sun always shines. 
They live in the house whose roof is full of holes.