英语语法讲解之定语从句时间：2016-08-12作者：来源：学习方法网一．几个基本概念1.定语从句的定义：用作定语的从句叫定语从句。
2.先行词：被定语从句所修饰的名词或代词。
3.定语从句的位置：紧跟先行词(名词或代词)之后。
4.引导词：引导定语从句的词(包括关系代词和关系副词)。
﹙1﹚关系代词：that/who/whom/which/as﹙2﹚关系副词：when/where/why5.引导词的位置：位于定语从句之前(先行词之后)。
【as除外】6.引导词的功能(作用)：﹙1﹚连接先行词和定语从句。
﹙2﹚在定语从句中充当一定的成分(关系代词充当主语或宾语，关系副词充当状语)。
7.定语从句的类型：﹙1﹚限定性定语从句(主句和定语从句之间无逗号)。
①直接由引导词引导定语从句The man who you’re talking to is my friend.②由介词+关系代词(whom/which)引导The man to whom you’re talking is my friend.I need a pen with which I can write a letter.=I need a piece of paper on which I can write a letter.介词的选用可根据从句中的相关词组确定，该介词通常可以放在关系代词之前，也可放在从句之尾。
例如：The man (who/whom/that) I talked about at the meeting is from Beijing University.=The man about whom I talked at the meeting is from Beijing University.The palace (which/that) I often pay a visit to was built in the 17th century.=The palace to which I often pay a visit was built in the 17th century.﹙2﹚非限定性定语从句(主句和定语从句之间用逗号隔开)。
①直接由引导词引导定语从句。
②由介词+关系代词(whom/which)引导。
I live in a house far away from the city，in front of which is a big tree.There is an apple tree standing at the gate，on which are many apples.This is the man to whom I gave the book.③由“代词/名词+of+whom/which”或“of which/ whom +名词/代词”(先行词指人用whom，指物用which)引导。
One，some，any，none，all，both，several，many，most，neither，either等词、数词、分数或百分比与of whom或of which连用。
He has five children，two of whom are abroad.(比较：He has five children，and two of them are abroad.)We have three books，none of which is/are interesting.(比较：We have three books，but none of them is/are interesting.)除why和that不能引导非限定性定语从句外，其余引导词都可以，用法同限定性定语从句一样。
但要注意以下区别。
1.在形式上非限定性定语从句与主句有逗号隔开。
2.非限定性定语从句的作用：它只是补充说明先行词的情况，翻译时可译成两个句子。
The engineer，whose leg was badly hurt，was quickly sent to hospital.(那位工程师被很快送往医院，其腿部受了重伤)The engineer whose leg was badly hurt was quickly sent to hospital.(那位腿部受了重伤的工程师被很快送往医院)3.在非限定性定语从句中，任何引导词都不能省略(包括引导词在此定语从句中充当宾语在内)。
指人做主语时只能用who，做宾语时用whom；指物做主语，宾语都用which；关系副词用when或where，也不能省略。
The man，______ is sitting on the chair，is my father.The woman，_______ I met yesterday，is my English teacher.The city，_______ is far away，is very beautiful.He went to America，______ his parents live.He joined the Army yesterday，______ I left，too.4.whose引导非限定性定语从句：The house，whose window faces south，is mine.=The house，the window of which faces south，is mine.=The house，of which the window faces south，is mine.二。
定语从句中关系代词和关系副词的基本用法。
1.who/that指人是主格在定语从句中代替先行词，又作定语从句的主语，不能省略。
Do you know the gentleman who/that is sitting there？2.whom/who/that指人是宾格，在定语从句中代替先行词，又作定语从句的宾语(动宾或介宾)。
①当作动宾(动词后接宾语)时，关系代词可省略。
Do you know the gentleman (whom/who/that) we met just now？②当作介宾(介词后接宾语)时：介词不提前时，关系代词可省略；介词提前时，关系代词不可省，即介词+whom(指人时介词后的关系代词只能用whom)。
The man (whom/who/that) I spoke with is my teacher.The man with whom I spoke is my teacher.※注：固定的动词短语(动词+介词)如look for，take care of等不能把动词与介词拆开，既介词不能提至引导词前。
She is the right girl (who/whom/that) we are looking for.3.whose：指人或物，是所有格“…的”形式。
Whose+n.一起在定语从句中充当主语、宾语(动宾或介宾)即先行词的什么东西怎样了，whose不能省略。
Whose+n. = the +n. + of which/whom= of which/ whom+ the =n.I didn’t find the desk whose leg was broken. (主语)He is the student whose pencil I broke yesterday. (动宾)The boss in whose company I work is very kind. (介宾)4.which/that 指物，指代先行词且在定语从句中作主语或宾语(动宾或介宾)。
①当作动宾时，关系代词可省略。
②当作介宾时：介词不提前时，关系代词可省略；介词提前时，关系代词不可省，即介词+which(指物时介词后的关系代词只能用which)。
The house which/that was destroyed in the earthquake is weak.The pen (which/that) you found yesterday is mine.The games (that/which) the young men competed in were difficult.The games in which the young men competed were difficult.※注：介词+关系代词即介词+whom/which(先行词指人用whom，指物用which)。
※5.as指人或物，在定语从句中可作主语，宾语，表语或状语，不能省略。
主要用于“the same …as…；such …as…；so …as…；as … as…；as follows”固定结构中，形式固定此时的引导限定性定语从句。
要用as代替who(m)，which，或that引导定语从句：Such people as knew Hill thought he was honest.Such people as Hill knew thought he was honest.My hometown is no longer the same as it was.Here is so big a stone as no one can lift.The child knows as much as grow-ups (know).I’d like to have the same books as are used in your school.He is not such a person as I expected.He will marry as pretty a girl as he can find.※注：which和as可引导非限定性定语从句：可以指代主句中的一部分或整个句子的内容，which和as都可以指代主句中的一部分或整个句子的内容，有时可以互换。
因此，当as/which指代前面的整个句子，或前句中的部分内容作定语从句的主语时，谓语用单数。
Our team lost the game，as/which was reported in the newspaper.She was terrified，as/which I could see from her eyes.He married her，as/which was natural.区别：①as引导的非限制性定语从句可以放在主句前面、插在主句中间或放在主句末尾；而which引导的非限制性定语从句只能放在主句后面。
He married her，as/which was natural.=As was natural，he married her.Mark Twin is a great writer，which/as is known to all.=As is known to all，Mark Twin is a great writer.②as引导的从句有“正如”、“正像”之意，而which则无此意。