【语法专项讲解】

定语从句

    在复合句中，修饰某一名词和代词，或修饰整个主句的从句叫做定语从句，它相当于形容词。被修饰的名词或代词叫先行词。

    引导定语从句的关系代词有who, whom, whose, which, that, as 和 关系副词 when, where, why。

    关系代词和关系副词既联系从句和先行词， 还在从句中充当一个成分。

关系代词

    1．Who （人， 主格，从句中作主语，非正式文体中代替whom作宾语，但是如果关系代词作介词的宾语，介词提前，就不用who，而用whom）

    The person to whom you spoke is a famous actor.

    The person who(whom) you spoke to is a famous actor.

    2．Whom （人， 宾格，从句中作宾语，非正式文体中常省略）

    3．Whose （多指人，也可物，指物可以与of which互换，从句中作定语）

    He mentioned a book whose author (= the author of which) I can't remember now.

    4．Which （指物，从句中作主语或宾语，宾语时常省略）

    关系代词whom, which作从句中介词的宾语，介词一般提前，也可放在后面。但如果从句中的介词为谓语的动词短语，介词不能提前，需紧挨动词。

    She sat on the corner of the table near the door by which her husband always entered.

    She sat on the corner of the table near the door which her husband always entered by.

    This is the key which you are looking for.

    但是先行词是时间，介词应放在关系代词which之前，不放在句尾。

    I'll never forget the day which I first met you on. (Χ)

    如果whom, which为介词宾语被省略，介词不能提前。

    I have the book you are talking about.

    The girl he leaned against was his sister.

    5. that （指人，也可物，从句中作主语或宾语，还可以作表语，作宾语或表语可以省略）

    He is not the man that he used to be.

    that 在从句中作介词的宾语，介词不提前，反之介词提前，必不用that.

    The house that we live in is not large.

    The house in which we live is not large.

    The house we live in is not large.

    That 指物可以与which互换，以下几种情况只用that.

    1）由不定代词anything, nothing, everything, all, one, little, few, much等充当先行词时。

    2）先行词被all, every, no, some, any, little, much 等修饰。

    3）先行词被序数词或形容词最高级修饰时。

    4）先行词被the only, the very, the same, the last 修饰时。

    That white flower is the only one that I really like.

    This is the very book that I want to have.

    The last place that we visited was the chemical works.

    5）有两个或两个以上的分别表示人和物的先行词，从句应用that,而不是其他。

    He talked about the teachers and schools that he had visited.

    6）当主句是以who, which 开头的特殊疑问句时，定语从句多用that,而不用who(whom),which.

    Who is the person that is standing at the gate?

    以上通常是使用于物，人一般不受限制，但如果正式和严谨可以遵循这一原则。

    6．as

    常用于 the same--- as, such ---as, as --- as , so --- as

    但 as 引导从句表示内容与主句相似，同类；that 表示内容与主句同一，同一事物。

    This is the same bag as I lost yesterday. This is the same bag that I lost yesterday.

    Such --- as 可以放在一起以such as 形式放在名词后。

    She collected a great many stories such as a child of four could understand.

    另外as 可以代表整个内容，前后都可以，但有逗号分开。

    As we have seen, oceans cover more than 70 % of the earth.

    As is known to all, Taiwan is a part of China.

    翻译为“正如---”。

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）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，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。

限制性和非限制性定语从句

    1）定语从句有限制性和非限制性两种。限制性定语从句是先行词不可缺少的部分，去掉它主句意思往往不明确；非限制性定语从句是先行词的附加说明，去掉了也不会影响主句的意思，它与主句之间通常用逗号分开，例如：

    This is the house which we bought last month.　　　

    这是我们上个月买的那幢房子。（限制性）

    The house, which we bought last month, is very nice.

    这幢房子很漂亮，是我们上个月买的。（非限制性）

    2）当先行词是专有名词或物主代词和指示代词所修饰时，其后的定语从句通常是非限制性的，例如：

    Charles Smith, who was my former teacher, retired last year.

    查理·史密斯去年退休了，他曾经是我的老师。

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

    我去年买的那幢房子带着个漂亮的花园。

    This novel, which I have read three times, is very touching.

    这本小说很动人，我已经读了三遍。

    3）非限制性定语从句还能将整个主句作为先行词, 对其进行修饰, 这时从句谓语动词要用第三人称单数，例如：

    He seems not to have grasped what I meant, which greatly upsets me.

    他似乎没抓住我的意思，这使我心烦。

    Liquid water changes to vapor, which is called evaporation.

    液态水变为蒸汽，这就叫做蒸发。

    说明：关系代词that和关系副词why不能引导非限制性定语从句。