英语语法口诀
第一部分 定语从句
1. 定语从句概述
a) 定语从句起定语修饰作用，分为限定性和非限定性两种，非限定性通常有逗号验证
I have plenty of friends who are from foreign countries.
I have plenty of friends, some of whom are from foreign countries.
b) 先行词，关系词，定语从句，如此一线性
The man that instructed me is a famous expert.
c) 关系词分为关系代词和关系副词两种，关系代词作主宾表定，关系副词作状语才行：关系词三大作用：1.代替先行词；2.引导从句；3.在从句中充当成分
The murder was caught alive in the house where he killed three women.
2. 三步法选关系词
a) 首先找出先行词，带入从句看成分是其次，（主表宾定不合适，状语必然是，用关系副词）再由先行词及其成分定关系词
I will never forget the day when I met the president.
3. 关系代词的选用
a) 人用that whom who。
b) which that 用于物
c) that 真是个人物，既充人又充物；既当宾又当主
d) whom 只做宾，which that who 既宾又主
e) whose 作定语（=名词+of which），不分人或物
The tall house whose windows face the south is my office.
4. 关系副词的选用
a) 先行词the time，需用关系副词时，用when 才可以
若关系词在从句中充当状语，则关系词应用when，the time +when（=on which）
I will never forget the days when I lived with you happily.
I will never forget the days which I spent learning English .
b) 先行词the place，需用关系副词时，where来效力
若关系词在从句中充当状语。则关系词应用where，the place+where（=in which）
c) 先行词the reason，需用关系副词时，why有用武之地
若关系词在从句中充当状语，则关系词应用why，the reason +why（=for which）
d) When where why都可用“相应介词+which”来代替
Why=for which; where=on/in/at which; when=on/in/at which
5. 某个关系词不能使用的情形和关系词的省略
a) 介词后不用that，who，而用which，whom
引导定从的关系词如果在介词后作介词宾语，则关系词不能用that和who
The train on which she was traveling was late.
Who is the girl to whom you speak?
b) 逗号后that资格不够
c) 限定性定从中关系词作宾或表，可去可留.注：在非限定性定语从句中，关系词一般不能省略。
6. 定语从句中的特殊情况
a) 插入语，先拿走，句子成分方可求
I married Bright, who I believed as an honest man.
I married Bright, whom I believed to be an honest man.
b) 先行词没有，the one/ones加前头
当被定从休息的先行词没有出现时，可以用the one或ones充当先行词。Is this problem the one you have thought of for ten years?
c) 先行词是one of+名词复数，定从谓复, 先行词是the only one of +名词复数，定从谓单
He is one of my friends who help me overcome difficulties.
He is the only one of my friends who helps me overcome difficulties.
7. 关系词as 和which的用法
a) As, which 引导非限制性定从，说明整个主句
b) As引导的从句与主句是一致关系
c) Which引导的从句与主句多是因果关系
d) As在句子中的位置随你意，which用于句首不可以
e) As充当主宾状，既充人又充物
f) The same。。。as；such。。。as搭配要牢记
8. 特殊情况关系词的选用
a) 1先行词是不定代词、数词、序数词、最高级，或被它们来修饰;2 only，very，no，little，few;3 有人又有物；4先行词在主句中作表语的结构；5或关系词在充剧中作标语的结构；上列情况每一种，关系词that抢占风头，which稍逊一筹
b) 1先行词是one，ones，anyone，those指人时;2 there be中修饰主语的定从，宜用who，不用that充
Anyone who breaks the law shall be punished.
There`s a fat man who wants to fight with you.
c) （口语中）关系副词可用that代替，也可省去
Every time that he takes part in the exam, he feels nervous.
d) 先行词是the way，用that，in which或省去
No one liked the way that/in which the teacher ordered us.
9. 其它
a) What(=all that)不能充当定语从句关系词
All that he said excited us.
b) 并列连词and，but，or，so一出席，此句往往与定语从句无关系
My mother bought lots of books, but they are useless.
c) But也可以引导定从作主语，带有否定意义
There was not a single person there but(=who didn`t think) thought you were fit for the job.
d) 先行词由关系词代替，它的其它形式要在定从中回避---否则会重复
Lei Feng is a man that we should all learn from him. 此句话错误，从句中不应出现him，应将其去掉。
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