定语从句,同位语从句,强调句的区别，希望详细点，谢谢

【四】定语从句：修饰前面某一名词或代词的从句叫定语从句。
由于在句中的作用相当于形容词，故也称为形容词性从句。
定语从句是由关系代词和关系副词引导的从句，其作用是作定语修饰主句的某尘散个成分，定语从句分为限定性和非限定性从句两种。限制性定语从句对被修饰词起到限制、修饰的作用，一般不可缺少。
非限制性定语从句起补充、附带说明作用，缺少也不会影响全句的理解。
一.限制性定语从句：限制性定语从句对被修饰词起到限制、修饰的作用，一般不可缺少。
1.由关系代词引导定语从句：关系代词：who, whom, whose, that, which, as等（在句中作主、表、宾、定等成分）
1. 关系代词在从句中作主语时，不能省略。
e.g. The classroom that is on the fourth floor is poorly equipped.
2. 关系代词在从句中作宾语且前面没有介词时，常可省略。
e.g. This is the girl with whom he works.
In this earthquake, the number of people who lost homes reached as many as 250,000.
I have many good friends to whom I am going to send postcards.
You’re the only person whose advice he might listen to.
The river which runs through the center of the city brings us a lot of pleasure.
He has given us as much advice as he can.

【例】The man to whom you talk just now is a famous runner.
【例】The service about which the students complain a lot should be improved.
【例】He is a library assistant from whom I borrowed some books.
【例】It is a famous school from which he graduated 3 years ago.
【例】The chair on which he is sitting now is made of wood.
The man (who/that/whom) you talk to just now is a famous runner.
【例】The service (which/that) the students complain about a lot should be improved.
He is a library assistant (whom/that/who) I borrowed some books from.
【例】It is a famous school (which/that) he graduated from 3 years ago.
【例】The chair (which/that) he is sitting on now is made of wood.
有一些动词短语中的介词是固定搭配，不可以拆开，一般还是放在动语之后，不提前：
【例】He is the student (who/whom/that) the teachers are looking for.
【例】The number of the children (who/whom/that) she takes care of is 3
【五】同位语从句
同位语从句与定语从句的区别（一）
同位语从句与定语从句形相似而实质不同，具体表现在以下几个方面：
1. 被修饰的词不同：同位语从句的前面一般是数量有限的、表示抽象意义的名词；而定语从句的先行词是无数的指仔晌人或物名词。
2. 从句的作用不同：同位语从句表示同位派戚氏名词的具体内容，而定语从句是对先行词的限制、描绘或说明。
3. 引导词不同：what, how, whether等不能用引导定语从句，但可用于引导同位从句。
4. 引导词的作用不同：引导同位语从句的that是连词，在从句中不充当任何成分；而引导定语从句的that为关系代词，在从句中充当一定的句子成分。
5. 判定定语从句和同位语从句的方法：由于同位语从句是用以说明被修饰名词的具体内容的，所它可以转换同位名词的表语；而定语从句则不能作这种转换。

同位语从句与定语从句的区别（二）

一、从句法功能上来看
同位语从句中连接词that在从句中不作句子成分，也没有词汇含义，只起连接作用，其作用大致相当于一个冒号；而引导定语从句的that是关系代词，且在句中充当句子的成分(主语或宾语)。如：
I hold the belief that where there is a will, there is a way. (that引导的是同位语从句，它在从句中不充当句子成分)
The letter that I received yesterday was from my sister. (that引导的是定语从句，它在从句中充当宾语)
二、从意义上来看
同位语从句所表达的内容与作为中心词的名词所表达的内容是一样的，两者之间可以划等号；而定语从句则是限制或修饰中心词的，中心词所表达的内容不等于定语从句所表达的内容。如：
He told me the news that his uncle would come home from abroad on National Day. (that引导的是同位语从句，其中the news = his uncle would come home from abroad on National Day)
This is the factory that we visited last month. (that引导的是定语从句，其中 the factory≠ we visited last month.)
三、从中心名词上来看
同位语从句中的中心名词常是一些表示概括意义的抽象名词，这类名词有fact, idea, view, thought, order, suggestion, news, truth, hope, promise, answer, belief, condition, doubt, fear, problem, proof, question 等。而定语从句中的中心名词是没有限定的。如：
四、从that是否可以省略来看
引导同位语从句的连词that一般不能省略，而在定语从句中，that作宾语时，可以省略。另外，引导定语从句的that若指事物，它可以用which来代替，而在同位语从句中，that 永远不能用which替代。
同位语从句的引导词问题

■最常用的引导词
用以引导同位语从句的最常用的连词是that。如：
The news that we are having a holiday tomorrow is not true. 明天放假的消息不实。
The idea that you can do this work without thinking is wrong. 你可以不动脑筋做此工作的想法是错误的。
有时也可以用whether、连接代词或连接副词等来引导。如：
It is a question how he did it. 那是一个他如何做的问题。
Do you have any idea where he lives? 你知道他住在哪里吗?
She had no idea why she thought of him suddenly. 她不明白她为什么突然想到了他。
We are not investigating the question whether he is trustworthy. 我们不是在调查他是否可信赖的问题。
■ 同位语从句可以用if引导吗
表示“是否”的whether可以引导同位语从句，但是与之同义的if不能用于引导同位语从句。如：
他是否会来还不一定。
误：There is some doubt if he will come.
正：There is some doubt whether he will come.
让我们来讨论是否该做的问题吧。
正：Let’s discuss the question if we should do it.
正：Let’s discuss the question whether we should do it.
■ 同位语从句可以用which引导吗
大家知道，在定语从句中，若先行词为指事物的名词，有时既可用that来引导定语从句，也可用which来引导定语从句，但在同位语从句中，习惯上要用that，而不用which。如：
我坚信他会获胜。
误：I hold a firm belief which he will win.
正：I hold a firm belief that he will win.
我得出结论这样做是不明智的。
误：I've come to the conclusion which it was unwise to do that.
正：I've come to the conclusion that it was unwise to do that.
■ 同位语从句可以用what引导吗
what不能用于引导定语从句，但可以引导同位语从句，尤其用于idea之后。如：
Have you any idea what time it starts? 你知道什么时候开始吗?
I didn’t have the faintest idea what you meant. 我一点也不明白你是什么意思。
Do you have any idea what it means to be poor? 你知道贫穷意味着什么吗?

一、强调句
为了突出某一部分重要信息，常常借用语法中的变换句子的正常语序，将某个成分置于句首或句末，或者通过词汇手段突出句子的某个成分。
1. it 为先行词的强调结构
It was Li Ping who told me the news. (强调人时才能用who)
It was in the park that I met him. (强调地点不能用where，只能用that)
It was yesterday that I saw him off at the airport. (强调时间不能用when，只能用that)
2. 助动词do 的强调作用
在行为动词作谓语的句子中，常用“助动词do或did” + 谓语“动词原形”表示强调语气。
例如：She did go to see him yesterday.
We do have four lessons in the morning.

一、定语从句与并列句式结构用法比较

在两个分句中，如果后一分句的主语指代前一分句中某一名词或整个句子的内容，且没有并列连词连接两个分句。这时，后一分句常用关系代词who(指人)，which(指物)，whose(指人或物)引导非限制性定语从句；如果两个分句间有and等并列连词连接，这时，后一分句常用人称代词或it, that代指前一分句中的某一名词或整个句子的内容，构成并列句式结构。

【例1】 (1) Dorothy was always speaking highly of her role in the play, which, of course, made the others unhappy. (NMET2000)

(2) Dorothy was always speaking highly of her role in the play, and it (that), of course, made the others unhappy.

比较：(1)两个分句间没有并列连词，后一分句的主语指代前一分句整个句子的内容(指物)，故要用关系代词which连接后一分句，构成非限制性定语从句。

(2)两个分句间有并列连词and连接，后一分句的主语指代前一分句整个句子的内容，故要用代词it 或that连接后一分句，构成并列句式结构。

【例2】 (1) I have heard from my father, who is in America.

(2) I have heard from my father, and he is in America.

比较：(1)两个分句间没有并列连词，后一分句的主语指代前一分句中名词my father(指人)，故要用关数轮系代词who连接后一分句，构成非限制性定语从句嫌键。

(2)两个分句间有并列连词and连接，后一分句的主语指代前一分句中名词my father，故要用人称代词he连接后一分句，构成并列句式结构。

【例3】 (1) Soon they came to a farmhouse, whose roof was much higher than others.

(2) Soon they came to a farmhouse, and its roof was much higher than others.

比较：(1)两个分句间没有并列连词，前一分句中名词farmhouse作后一分句中主语的定语(为所属关系)，故要用关系代词whose连接后一分句，构成非限制性定语从句。

(2)两个分句间有并列连词and连接，前一分句中名词farmhouse作后一分薯者信句中主语的定语(为所属关系)，故要用代词it连接后一分句，构成并列句式结构。

二、定语从句与分词结构用法比较

在同一个句子结构中，如果含有两个谓语动词，一般来说，置于中心名词后作修饰语的动词或动词短语常用分词作后置定语，也可转换成相应的定语从句。如果中心名词为动作的执行者，常用现在分词作后置定语。这时，现在分词可转换成一般现在(过去)时或现在(过去)进行时的定语从句结构。如果中心名词为动作的被执行者，常用过去分词作后置定语。这时，过去分词可转换成被动语态的一般过去时或进行时的定语从句结构。

【例1】 (1) There was a terrible noise following the sudden burst of light. (NMET97)

(2) There was a terrible noise that followed the sudden burst of light

比较：(1)从句子结构分析，动词follow作中心名词a terrible noise 的后置定语，但句中没有关系代词连接,且中心名词a terrible noise为动词follow动作的执行者，故要选用动词的分词形式following作后置定语。

(2)从句子结构分析，动词follow作中心名词a terrible noise 的后置定语，但由于句中有关系代词that连接,且中心名词a terrible noise为动词follow动作的执行者，故要选用动词的过去式形式followed与that一起构成定语从句结构。

【例2】 (1) The Olympic Games, first played in 776 B.C., didn't include women players until 1912. (NMET 1997)

(2) The Olympic Games, which was first played in 776 B.C., didn't include women players until 1912.

比较：(1)分析句子结构可知，插入语first played in 776 B.C. 作中心名词the Olympic Games的定语，但句中没有关系代词连接,同时中心名词the Olympic Games为动词play动作的被执行者且发生在过去某一时刻，故要选用动词的过去分词形式played作后置定语。

(2)分析句子结构可知，插入语first played in 776 B.C. 作中心名词the Olympic Games的定语，但句中有关系代词which连接,同时中心名词the Olympic Games为动词play动作的被执行者且发生在过去某一时刻，故要用动词的被动语态结构和关系代词which一起构成非限制性定语从句作后置定语。

三、 定语从句与强调句句式结构用法比较

由it引导的句型结构，常可构成强调句或定语从句，两者极易混淆。一般来说，如果将it is/was...与连接词去掉，句子仍然正确，就为强调句型。这时，就选用that连接词；否则，就为定语从句，其关系词的选择，应根据先行词与从句的关系而定。

例1. (1) It is on the island that they spent 10 years.

(2) It is the island where (on which) they spent 10 years.

比较：(1)该句为强调句。表示地点的名词the island前有介词与其连用，说明它是一个完整的地点状语。如果将it is去掉：They spent 10 years on the island.它的意义仍然完整。故应选用连接词that构成强调句式 (注：强调地点状语时，不可用where连接)。

(2)该句为定语从句。表示地点的名词the island前没有介词与其连用，说明它不是一个完整的地点状语。如果将it is去掉：They spent 10 years the island.它的意义不完整。故应选用关系副词where或on which 构成定语从句结构。

例2. (1) It is on the date that she went abroad.

(2) It is the date when(on which) she went abroad.

比较：(1)分析句子结构可知，在表示时间的名词the date 前有介词与其连用，说明它是一个完整的时间状语。如果将it is去掉：She went abroad on the date.它的意义仍然完整。故应选用连接词that构成强调句式(强调时间状语时，不可用when连接)。

(2) 分析句子结构可知，在表示时间的名词the date 前没有介词与其连用，说明它不是一个完整的时间状语。如果将it is去掉：She went abroad the date.它的意义不完整。故应选用关系副词when或on which 构成定语从句结构。

四、定语从句与名词性从句句式结构用法比较

定语从句常易与主语从句、表语从句、宾语从句和同位语从句等名词性从句相混淆。判断的方法是：由关系代词或副词引起的句子直接充当句中某一成分，即为名词性从句；如果这个句子修饰前面的一个名词即先行词或指代整个句子的内容，即为定语从句。

例1. (1) As is known to everyone , the moon travels round the earth once every month. (NMET2001)

(2) It is known to everyone that the moon travels round the earth once every month.

比较：(1)两个句子之间没有连接词，而是由逗号分隔。根据前一分句意义"正如大家所知道的(众所周知)"分析，该句应用关系代词as引导非限制性定语从句，指代主句整个句子内容。

(2)两个句子之间有连接词that连接。根据句意分析，that所引起的从句为主语从句，故该句应选用it作形式主语置于句首，引导主语从句。

例2. (1)Shenzhen is no longer what it used to be.

(2) Shenzhen is no longer the place that it used to be.

比较：(1)句中没有充当表语的名词，故应选用代词what(……样子)引起一个表语从句。

(2)句中表语名词the place 被it used to be所修饰，且充当其句中表语。故应选用关系代词that指代先行词the place引起一个定语从句。

例3. (1) Please tell me the reason why he didn't attend the meeting.

(2) Please tell me why he didn't attend the meeting.

比较：(1)句中充当宾语的名词the reason被he didn't attend the meeting所修饰，且充当句中的原因状语。故应选用关系副词why指代先行词the reason连接定语从句。

(2)句中没有充当直接宾语的名词，而是由一个句子充当宾语。根据句意，应选用疑问副词why连接宾语从句。

例4. (1) The fact puzzles me much that I have been unable to pass the driving test up to now.

(2) Do you understand the easier fact that (which) he explained to you just now?

比较：(1)根据句意分析，从句I have been unable to pass the driving test up to now 是来解释说明句中主语 the fact，是同位关系，且the fact不充当句中任何成分。故应选用连接词that连接同位语从句。

(2)分析句子结构可知，句中名词the easier fact在后一从句中充当宾语。故应选用关系代词that(which) 指代先行词the easier fact 连接定语从句。

五、定语从句与状语从句句式结构用法比较

定语从句常极易混淆于结果状语或地点状语等从句。一般来说，如果连接从句的连接词在从句中指代先行词充当某一成分，即为定语从句。反之，仅起连接作用，即为状语从句。

例1. (1) Would you please put the book back in the place where it should be?

(2) Would you please put the book back where it should be?

比较：(1)句中连接词where指代表示地点的先行词in the place，在从句中充当地点状语。故where 为关系副词，引导定语从句，也可用in which替代。

(2)根据句意分析，该句应选用表示地点的副词where连接从句。分析句子结构，句中无先行词被从句修饰，故副词where引导的从句仅为地点状语从句。这时，不可用in which替代。

例2. (1) It is such a modern machine that few of the workers know how to operate it.

(2) It is such a modern machine as few of the workers know how to operate.

比较：(1)分析句意可知，连接词that在句中不充当句子任何成分，仅起连接作用。意为"如此……以致……"。故该句为结果状语从句。

(2)句中连接词，在从句中充当句子成分，作宾语，指代先行词a modern machine。根据句子结构"such..."，应选用关系代词as 连接定语从句。