对于英语不好的同学来说，学习语法是至关重要的，下面是Unit5Music重点语法讲解，请大家及时查看学习。

被修饰的词叫先行词。定语从句不同于单词作定语的情况，它通常只能放在被修饰的词(即先行词)之后。定语 从句由关系词(关系代词、关系副词)引导，关系代词、关系副词位于定语从句句首。

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?

他就是想见你的人吗?(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。

3)which, that

它们所代替的先行词是事物的名词或代词，在从句中可作主语、宾语等，例如：

A prosperity which / that had never been seen before appears in the countryside. 农村出现了前所未 有的繁荣。(which / that在句中作主语)

The package which / that you are carrying is about to come unwrapped. 你拿的包快散了。(which / that 在句中作宾语)

关系副词引导的定语从句

关系副词可代替的先行词是时间、地点或理由的名词，在从句中作状语。

1)when, where, why

关系副词when, where, why的含义相当于"介词+ which"结构，因此常常和"介词+ which"结构交替使用，例 如：

There are occasions when (on which) one must yield. 任何人都有不得不屈服的时候。

Beijing is the place where (in which) I was born. 北京是我的出生地。

Is this the reason why (for which) he refused our offer? 这就是他拒绝我们帮助他的理由吗?

2)that代替关系副词

that可以用于表示时间、地点、方式、理由的名词后取代when, where, why和"介词+ which"引导的定语从 句，在口语中that常被省略，例如：

His father died the year (that / when / in which) he was born. 他父亲在他出生那年逝世了。

He is unlikely to find the place (that / where / in which) he lived forty years ago. 他不大可能找到他四十 年前居住过的地方。

判断关系代词与关系副词

方法一： 用关系代词，还是关系副词完全取决于从句中的谓语动词。及物动词后面无宾语，就必须要 求用关系代词。例如：

(错) This is the mountain village where I visited last year.

(错) I will never forget the days when I spent in the countryside.

(对) This is the mountain village (which) I visited last year.

(对) I'll never forget the days (which) I spent in the countryside.

习惯上总把表地点或时间的名词与关系副词 where, when联系在一起。此两题错在关系词的误用上。

方法二： 准确判断先行词在定语从句中的成分(主、谓、宾、定、状)，也能正确选择出关系代词/关系 副词.先行词在从句中作主、定、宾语时，应选择关系代词;先行词在从句中作状语时，应选 择关系副词。

例如：(对)Is this the museum which you visited a few days ago?

(对)Is this the museum where the exhibition was held?

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