限制性定语从句的概念：

限制性定语是指对被修饰名词或代词的必需修饰，是被修饰名词或代词不可缺少的修饰语，如果去掉它句子意思往往会不明确或会发生变化。
如：The travellers knowing about the floods took another road. 知道发大水的那些游客改道走了。
        The boys wanting to play football were disappointed when it rained. 想踢足球的那些男孩子因为下雨而感到失望。

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：
例：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ofwhich互换）
例：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) coverisgreen. 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在句中作宾语）
            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(inwhich) 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。

限定性定语与非限定性定语的区别：

1、形式不同：
限定性定语从句主句和从句之间不用逗号隔开，口语中使用时也不停顿；而非限定性定语从句与主句之间通常有逗号隔开，口语中使用时有停顿。
2、功能不同：
 限定性定语从句用于对先行词的意义进行修饰、限制和识别，如果去掉，就会造成句意不完整或概念不清；而非限定性定语从句用于对先行词起补充说明作用，如果省略，句意仍然清楚、完整：
如：People who take physical exercise live longer. 进行体育锻炼的人活得长些。(若把从句去掉句子就失去意义)
        His daughter, who is in Boston now, is coming home next week. 他女儿现在在波士顿，下星期回来。(若把从句去句子意义仍然完整)
3、翻译不同：
在翻译定语从句时，一般把限定性定语从句翻译在它所修饰的先行词之前，而把非限定性定语从句与主句分开：
如：He is the man whose car was stolen. 他就是汽车被窃的那个人。
        I've invited Jim, who lives in the next flat. 我邀请了吉姆，他就住在隔壁。
4、含义不同：
如：I have a sister who is a doctor. 我有一个医生的姐姐。(姐姐不止一个)
        I have a sister, who is a doctor. 我有一个姐姐，她是当医生的。(只有一个姐姐)
5、先行词不同限定性定语从句的先行词只能是名词或代词，而非限定性定语从句的先行词则可以是名词或代词，也可以是短语或句子；
另外，当先行词为专有名词或其他具有独一无二性的普通名词时，通常要用非限制性定语从句，而不用限制性定语从句：
如：Peter drove too fast, which was dangerous. 彼得开车很快，这是很危险的。(which指drive too fast)
        He changed his mind, which made me very angry. 他改变了主意，这使我很生气。(which指整个主句)
        Mr.Smith, who is our boss, will leave for Japan next week. 我们的老板史密斯先生下周要去日本。(先行词为专有名词，要用非限制性定语从句修饰)  
        Her father, who has a lot of money, wishes her to study abroad. 她父亲很有钱，希望她出国学习。(先行词为表独一无二意义的普通名词，要用非限制性定语从句修饰)
6、关系词不同：
关系词that和why可用于限制性定语从句中，通常不用于非限制性定语从句；另外，在限制性定语从句中，关系词有时可以省略，而在非限制性定语从句中关系词一律不省略。

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；而不及物动词则要求用关系副词。
例如：This is the mountain village where I stayed last year.
            I'll never forget the days when I worked together with you.
判断改错
（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.
注：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。
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。
例1. Is this museum ___ you visited a few days age?
        A. where 
        B. that
        C. on which
        D. the one
例2. Is this the museum ____ the exhibition was held.  
        A. where 
        B. that
        C.on which
        D. the one
答案：例1：D，例2：A
例1变为肯定句：This museum is___ you visited a few days ago.
例2变为肯定句：This is the museum ___ the exhibition was held.
注：在句1中，所缺部分为宾语，而where, that, on which都不能起到宾语的作用，只有the one既做了主句的表语，又可做从句的宾语，可以省略关系代词，所以应选D。
而句2中,主、谓、宾俱全，从句部分为句子的状语表地点，既可用副词where，又因in the museum词组，可用介词in+which引导地点状语。
而此题中，介词on用的不对，所以选A。关系词的选择依据在从句中所做的成分，先行词在从句中作主、定、宾语时，选择关系代词(who,whom,that,which,whose)；
先行词在从句中做状语时，应选择关系副词(where地点状语，when时间状语，why原因状语)。

定语从句知识体系：

关系代词that的用法：

1）不用that的情况：
a)在引导非限定性定语从句时。
如：（错）The tree, that is four hundred years old, is very famous here.
b)介词后不能用：
如：We depend on the land from which we get our food.
        We depend on the land that/which we get our food from.
2)只能用that作为定语从句的关系代词的情况
a)在there be句型中，只用that，不用which。
b)在不定代词，如：anything, nothing, the one, all, much, few, any, little等作先行词时，只用that，不用which。
c)先行词有the only, the very修饰时，只用that。
d)先行词为序数词、数词、形容词最高级时，只用that。.
e)先行词既有人，又有物时。
例：All that is needed is a supply of oil.  所需的只是供油问题。  
        Finally, the thief handed everything that he had stolen to the police. 那贼最终把偷的全部东西交给了警察。

强调句的概念：

强调句 (The Emphatic Pattern) 是一种修辞，是人们为了表达自己的意愿或情感而使用的一种形式。通过各种方式对句子中的某个部分进行强调，从而起到修辞的作用。英语常用的强调结构有：It is (was)+被强调部分(主语、宾语或状语)+that/who...；what…be…句型；

强调句的使用:

一、强调句句型：
1、用It is／was...that／who...句型表示强调。
（1）陈述句的强调句型：It is/was+被强调部分（通常是主语、宾语或状语）+that/who（当强调主语且主语指人）+其它部分。
e.g. It was yesterday that he met Li Ping.
（2）一般疑问句的强调句型：同上，只是把is/was提到it前面。
e.g. Was it yesterday that he met Li Ping?
（3）特殊疑问句的强调句型：被强调部分（通常是疑问代词或疑问副词）+is/was+it+that/who+其它部分？
e.g. When and where was it that you were born?
注：被强调的部分（通常是句子的主语、状语、宾语或宾语补足语）放在is／was的后面，如被强调的是人，则后面可用who，whom等代替。
如：原句：He met an old friend in the park yesterday.  
        强调主语：It was he who/that met an old friend in the park yesterday.
        强调宾语：It was an old friend that/who he met in the park yesterday. 
        强调地点状语：It was in the park that he met an old friend yesterday. 
        强调时间状语：It was yesterday that he met an old friend in the park.
2、用助动词do, does或did来强调谓语动词。
如：Do come early. 
        He did send you a letter last week.
        We're pleased that she does intend to come.
3、用主语从句+be+被强调部分，主语从句常用what引导。
如：What John wants is a ball.
        What Mary does every day is(to) give piano lessons.  

二、not...until...句型的强调句：
1、句型为：It is/was not until+被强调部分+that+其它部分：
e.g. 普通句：He didn't go to bed until/till his wife came back. 
       强调句：It was not until his wife came back that he went to bed.
2、注意：此句型只用until，不用till。但如果不是强调句型，till, until可通用；
因为句型中It is/was not...已经是否定句了，that后面的从句要用肯定句，切勿再用否定句了。

三、谓语动词的强调：
1、It is/was...that...结构不能强调谓语，如果需要强调谓语时，用助动词do/does或did。
e.g. Do sit down.务必请坐。
      He did write to you last week. 上周他确实给你写了信。
      Do be careful when you cross the street. 过马路时，务必（千万）要小心啊！
2、注意：此种强调只用do/does和did，没有别的形式；过去时用did，后面的谓语动词用原形。 

使用强调句型有以下几点请注意：

①强调句的谓语is或was永远用单数。
如：It was yesterday that I met your father in the street.
②不管被强调部分是哪种状语，只能用that连接，不得使用where、when等连词。
如：It was in the street that I met your father yesterday.
③被强调部分为人时，可用who(主格或宾格)和whom(宾格)代替that，用that也行。
如：It was your father that/whom/who I met in the street yesterday.
        It was I that/who met your father in the street yesterday.
④强调句中也要注意主谓一致、人称一致和否定转移的问题。
如：It is they who are our friends.
        It was not until ten o'clock that we got home last night.
⑤注意不要混淆强调句和其他从句。It is/was...that...为强调句标志，去掉后仍可组成一个完整的句子，只是没被强调，而其他从句一般不具备这一特征。
比较：1）It was ten o'clock when we got home last night. 我们昨晚到家时已十点了。
            2）It was at ten o'clock that we got home last night. 我们昨晚是在十点到家的。
第一句不是强调句，when不可改为that，因为去掉it was和that后，只能组成“We got home ten o'clock last night.”这样一个不完整的句子；第二句是强调句，that不可改为when。

强调句型用法拓展：

1、句首词用“It”，不能用“This”，“That”等。
2、be动词的形式是is或was，不能用复数形式are或were。若原句的谓语动词用了现在时或将来时，则用is；
若原句的谓语动词用了过去时或过去完成时，则用was。
如：It___the Chinese women that___a great role in the socialist construction.
A. is; plays
B. are; play
C .is; play
D. are; plays
答案：C 
3、被强调的部分如果是代词，强调主语用主格，强调宾语用宾格。
如：It is him that/who/whom I met in the street yesterday.
        It is I who/that am wrong.
4、连接词一般用that，当强调部分是人时，既可用that也可用who。特别注意当强调部分是时间状语或地点状语时，不能用when或where。
如：It was on Oct1st, 1949 that People's Republic of China was founded.
        It was at the gate____he told me the news.　　
        A. that
        B. what
        C. which
        D. when
答案：A
5、主谓一致问题被强调的主语要和that后面的谓语动词在数上保持一致。
如：It is Mary who often _____(help) me with my English. （helps）
        It is I that ____(be) against you. （am）
6、not...until结构的强调。
强调“not...until”引导的时间状语时，要用“it is/was not until...that...”结构，that后面的句子要用肯定式，且须用陈述句语序。 
如：We did not get off the bus until it stopped. ?
        It was not until it stopped that we got off the bus. (注意：强调该结构时not until不能分开)