Relative clauses add extra information to a sentence by defining a noun. They are usually divided into two types –defining relative clauses and non-defining relative clauses.
定語(yǔ)從句是對(duì)句子里的名詞加入額外的信息。一般來(lái)講，有兩種類型的定語(yǔ)從句—限定性定語(yǔ)從句和非限定性定語(yǔ)從句。

Defining relative clauses
限定性定語(yǔ)從句

Look at this sentence:
看如下例句：
? The woman who lives next door works in a bank.
‘who lives next door’ is a defining relative clause. It tells us which woman we are talking about.
‘who lives next door’就是限定性定語(yǔ)從句，它告訴我們我們正在談?wù)摰哪莻€(gè)“女人”的更多信息。
Look at some more examples:
看看更多的例句：
? Look out! There’s the dog that bit my brother.
? The film that we saw last week was awful.
? This is the skirt I bought in the sales.
Can you identify the defining relative clauses? They tell us which dog, which film and which skirt we are talking about.
你能認(rèn)出上面句子中的限定性定語(yǔ)從句嗎？

Relative pronouns
關(guān)系代詞

Relative clauses are often introduced by a relative pronoun (usually who, which, that, but when, where and whose are also possible)
定語(yǔ)從句經(jīng)常由關(guān)系代詞連接（一般是who, which, that, 不過(guò)when, where 和whose也是可能的）
With defining relative clauses we can use who or that to talk about people.
在限定性定語(yǔ)從句里，我們能用who和that來(lái)指代和談?wù)搫e人。
? She’s the woman who cuts my hair.
? She’s the woman that cuts my hair.
And we can use that or which to talk about things.
然后，我們用that和which來(lái)指代和談?wù)撌挛铩?/div>? The dog that bit my brother.
? The dog which bit my brother.
It is also sometimes possible to omit the relative pronoun.
有時(shí)候，也可以省略關(guān)系代詞。
? This is the skirt that I bought in the sales.
? This is the skirt which I bought in the sales.
? This is the skirt I bought in the sales.
In this sentence ‘skirt’ is the object of the verb (buy). ‘I’ is the subject. When the relative pronoun is the object, it can be omitted.
在句子中，skirt是動(dòng)詞buy的賓語(yǔ)，而I 是主語(yǔ)，當(dāng)關(guān)系代詞是賓語(yǔ)的時(shí)候，它可以被省略。
? The film we saw last week was awful.
? BUT The dog bit my brother. This is not possible because the dog is the subject of the verb, ‘bite’.