限制性定语从句与非限制性定语从句

限制性定语从句与非限制性定语从句

1. 基本区别

根据定语从句与先行词的关系，可将定语从句分为限制性定语从句和非限制性定语从句。一般说来，限制性定语从句是整个句子不可缺少的部分，如果省略会影响全句的主要思想，这种定语从句前面一般不用逗号；而非限制性定语从句则只是主句的一种补充说明，即即使去掉，也不会影响全句的主要思想，这种定语从句前通常有逗号隔开。如：

This is the book that you want. 这就是你要的那本书。

句中的you want为限制性定语从句，如果去掉，意思就不清楚。

He bought me a book, which was very useful. 他给我买了一本书，非常有用。

句中的which was very useful为非限制性定语从句，如果去掉，句子意思仍是清楚的。

2. 关系词的区别

关系代词that和关系副词why通常只用于引导限制性定语从句，不用于引导非限制性定语从句。如：

她收到了老板的邀请，这是她意想不到的。

误：She received an invitation from her boss, that came as a surprise.

正：She received an invitation from her boss, which came as a surprise.

他失去工作的主要原因是他喝酒。

误：The main reason, why he lost his job, was that he drank.

正：The main reason why he lost his job was that he drank.

另外，在限制性定语从句中，关系代词which用作宾语时，如果不是紧跟在介词之后，通常可以省略；但在非限制性定语从句中，不管在什么情况下均不可省略关系代词which。

3. 用法注意

当一个名词已由其他词语作了完整的表述，这个名词后则不宜再用限制限制性从句，而应改用非限制性定语从句。如：

我去看买的房子有一个很漂亮的花园。

误：My house which I bought last year has got a lovely garden.

正：My house, which I bought last year, has got a lovely garden.

若要用限制性定语从句，则应将物主代词my改为the，即说成：

The house which I bought last year has got a lovely garden.

4. 补充说明

非限制性定语从句有时形式上是从句，实质上其功用相当于一个并列的分句。如：

He said he had no money, which was not true. 他说他没有钱，这不是实话。(which相当于but it)

Then he met Mary, who invited him to a party. 后来他遇到玛丽，玛丽邀请他去参加晚会。(who相当于and she)

My father may have to go into hospital, in which case won’t be going on holiday. 我父亲可能需要住院，如果那样他就不去度假了。(in which case相当于and in that case)