定语从句又称为形容词性从句.
定语从句在句子中起定语作用,修饰一个名词或代词,有时也修饰一个句子.
(就像形容词修饰名词那样,如 a happy boy, happy是形容词,修饰名词boy.一个男孩,具体是什么样的小男孩,就由形容词happy来修饰boy,happy在短语中做定语,限定boy的特征,一个快乐的男孩.)
同样道理,定语从句也是用来修饰名词等,限定名词的特征.
但是与上面所举的短语例子不同的是,定语从句必须放在先行词后面.(先行词就是被定语从句修饰的词.)
如:This is the place which we visited.
这句话中,which we visited是定语从句, the place是先行词,
定语从句修饰先行词the place,这是一个地方,是怎么样一个地方呢?就由定语从句来说明,"这是我们参观过的地方".
还有一个要点就是定语从句的引导词,定语从句由关系代词或关系副词引导,关系词充当从句的成分.
which就是关系代词,在定语从句中做宾语.
因为从句we visited.缺少宾语,所以由which充当,完整表示为
we visited the place.
定语从句的特点
定语从句（Attributive Clauses）在句中做定语，修饰一个名词或代词，被修饰的名词,词组或代词即先行词。定语从句通常出现在先行词之后，由关系词（关系代词或关系副词）引出。
关系代词有：who, whom, whose, that, which等。
关系副词有：when, where, why等。
关系代词引导的定语从句
关系代词所代替的先行词是人或物的名词或代词，并在句中充当主语、宾语、定语等成分。关系代词在定语从句中作主语时，从句谓语动词的人称和数要和先行词保持一致。
1）who, whom, that
这些词代替的先行词是人的名词或代词，在从句中所起作用如下：
Is he the man who/that wants to see you?
他就是你想见的人吗？（who/that在从句中作主语）
He is the man whom/ that I saw yesterday.
他就是我昨天见的那个人。（whom/that在从句中作宾语）
2） Whose 用来指人或物，（只用作定语, 若指物，它还可以同of which互换）, 例如：
They rushed over to help the man whose car had broken down. 那人车坏了，大家都跑过去帮忙。
Please pass me the book whose （of which） cover is green. 请递给我那本绿皮的书。
定语从句练习题
1.The young film star receives hundreds of letters a day, her parents both pleasure and worry.
A.which brings B. that brings C. which bring D. that have brought
2.There were two small rooms in the house, served as kitchen.
A.the smaller of which B. the small of them C. the smaller of them D. the smaller one
3.All of the flowers now raised by her have developed from those in the forest.
A.once they B. they grew once C. that once grew D. once grew
4.Last night I came across a man I think is a pleasant to .
