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【摘要】定语从句是中学英语教学的重点，也是学生学习的难点，同时又是高考考查的热点。但是学生在学习过程中出现了模糊的理解，所以我结合自己的教学经验对此作了总结，以供大家参考。
【关键词】定语；关系词；成份；用法
College entrance examination English attributive clause examination site analysis
Yan Xiaomei
【Abstract】The attributive clause is the middle school English teaching key point, is also the difficulty which the student studies, simultaneously is also the hot spot which the college entrance examination examines. But the student presented the fuzzy understanding in the learning process, therefore I unified my teaching experience to make the summary regarding this, by for everybody reference.
【Key words】Attribute; Relational word; Ingredient; Usage
在复合句中，修饰主句中某一名词/代词的从句称为定语从句。被修饰的词称为先行词；引导定语从句的词叫关系词。关系词的作用：1）连接主从句 2）代替先行词在从句中担任成分。所以学习定语从句，可以分三步走：第一找出先行词；第二看先行词在定语从句中的语法功能（做主语、宾语或状语）；第三选择合适的关系词。搞清楚关系词在定语从句中所起的作用是非常关键的。
e.g. He is a student whostudies hard.（在定语从句中作主语）
先行词 关系词 定语从句
关系词的用法：
1）关系代词：who, whom, whose, that, which 在定语从句中作主语、宾语和定语。
who指人,作主语或宾语 (作宾语可省略）
eg: (1) The man who visited our school yesterday is Mr Brown.
(2) The boy （who ）we saw yesterday is Jack.
whom指人,作宾语 (作宾语可省略)
eg:(1) The man（whom）you are going to visit is a famous writer.
(2) Have you met the person （whom）he was speaking about?
whose : 指人或物，作定语，表示 …的。whose从句也可转换为“ the+n.+of +关系代词”型，如：
(1) Harry is the boy whose mother is our Maths teacher.
(2) I saw some trees whose leaves were black.
(3) They live in a house, whose door opens to the south.
→They lived in a house, the door of which open to the south.
→They lived in a house, of which the door opens to the south
which 指物，作主语或宾语 (作宾语可省略)
eg: (1) These are the trees which were planted last year.
(2) This recorder （which） he is using is made in Japan.
(3) Is this the library (which) you borrow books from?
that 指人/物，作主语或宾语 (作宾语可省略）
eg: (1) A plane is a machine that can fly.
(2) He is the man (that) I told you about.
(3) Let’s ask the man that is reading the book over there.
(4) The girl (that) we saw yesterday is Jim’s sister.
(5) The cakes (that) I cooked were delicious.
2）关系副词：当先行词为表示时间，地点，原因的名词，而且在定语从句中作时间，地点和原因状语，用when, where, why .
考点一：关系代词that和which的区别：
1.以下情况，引导词用that，不用which。
1) 先行词为不定代词everything，little，much，all，anything，nothing。或者先行词 被all, much, little, some, any, every, no 等词修饰时;
e.g. Finally, the thief handed everything that he had stolen.
典型例题：
His brother didshe could to help him.
A. all which B. all what C. all D. which
[解析]句中did是及物动词，后缺少宾语，而could后又省略了动词do，所以用all作did的宾语，all后面省略了关系代词that，故答案选C。
2) 先行词前有形容词最高级、序数词修饰时，用that。
e.g. This is the best book (that) I’ve ever read.
3) 先行词被the only（唯一的），the very（正是那个），the last等 修饰时，用that。
e.g. He is the only person that I want to see now.
4) 先行词同时指人和指物时，用that。
e.g. We talked about the things and persons that we saw then.
Do you know the things and persons that they are talking about?
5) 在疑问词who、which、what开头的句子中
eg. Who is the man that is standing over there?
Which of those books that are on the table belong to you?
6) 当先行词在主句中作表语，而关系代词也在从句中作表语时，用that。
eg. Shanghai is no longer the city that it used to be.
Exx.1.This is all I know about the matter.
A. that B. what C. who D. whether
2.Is there anything else you want?
A. which B. thatC. who D. what
3. The last place we visited was the Great Wall.
A. which B. that C. where D. it
4. Please take the second chairis over there.
A. whereB. which C. who D. that
5. Is oxygen the only gashelps fire burn?
A. that B./ C. which D. it
6.Finally, the thief handed everything he had stolen to the police（NMET98’)
A. whichB. whatC. whatever D. that
2. 只用which，不用that的情况：
1）引导非限制性定语从句修饰某物或整个句子时, 不能用that;
e.g. Bruce went towards the fire, which was still smoking.
2）关系代词前有介词前置时,不能用that;
e.g. This is the classroom （that/which）we study in.
This is the classroom in which we study.
Do you remember the day on which you joined our club?
3）一个句子中若有两个定语从句，一个已经用that引导，另一个用which引导；
e.g. He bought a book that could give him much knowledge and which could help him to kill the time.
典型例题：
Her sister has become a lawyer,she wanted to be. (05’湖北卷)
A. whoB. thatC. whatD. which
[解析] 先行词lawyer尽管是人，但这儿表示职业，这是一个非限制性定语从句，关系代词在句中作宾语，只能用which ，不能用that，所以答案选D。
e.g. This is the house in which I lived two years ago.
Do you remember the day on which you joined our
club?
I have got a writing brush with which I can write.
考点二：介词+关系代词
1. 当关系代词作介词宾语，且该介词不是和从句的谓语动词构成固定短语时，介词可以提前，这样就出现“介词+关系代词”。先行词指物，用“介词+which/whose”, 指人则用 “介词+whom/whose”, 且两个关系代词均不能省略，介词的选择要遵循三个原则：
(1) 根据从句中动词与先行词的逻辑关系，
e.g. Is that the newspaper for which you often write articles?
典型例题：
I saw a woman running towards me in the dark. Before I could recognize who she was，she had run back in the direction she had come. (06’重庆卷)A. of which B. by which C. in which D. from which[解析]此题考查由“介词+关系代词”引导的定语从句，根据句意用from which表示“所来的那个方向”，故答案选D。
（2） 根据从句中动词或形容词的习惯搭配，如：
e.g. Can you explain to me how to use theseidioms about which I’m sure.
典型例题：
In the dark street, there wasn’t a single person she could turn for help.
A. that B. who C. from whom D. to whom
[解析] 在此句中，定语从句中缺少宾语，考查介词的选择，根据固定搭配turn to sb for help,所以选择答案D
(3) 根据定语从句表达的意义来确定。
Air, without which man can’t live, is really important.
2. 在非限制性定语从句中，要表示先行词的一部分时，可用“数词/代词 + of + 关系代词”的结构，如：
e.g. There are 50 students in our class, two-thirds of whom have been to Beijing.
典型例题：
There are two buildings, stands nearly a hundred feet high . （04’湖北卷）
A. the larger B. the larger of them C. the larger one that D. the larger of which
[解析] the larger of which指代the larger of the two buildings ，which 在定语从句中指代 building，作介词of的宾语，故答案为D。
注意： 如果定语从句中的介词短语是固定搭配，则介词应放在动词之后，不能拆开放在关系代词前。例如：
e.g:(1) This is the key which you are looking for.
(2) This is the baby whom you will look after.
(3) He is the man who I am looking at.
3. 根据定语从句表达的意义来确定。
Air, without which man can’t live, is really important.
考点三；whose 在从句中作定语，指人或物
whose从句可转换为“of +关系代词”型，即：whose+ n.=the +n.+of which/whom=of which/whom +the + n.
e.g. They live in a house, whose door opens to the south.
They lived in a house, the door of which open to the south.
They lived in a house, of which the door opens to the south.
考点四:考查关系副词where、when与why引导的定语从句
它们相当于“介词+which”，其中where = in/ at +which; when= on/ in /during +which ; why = for+ which
(1)关系副词 where引导定语从句时，只能在定语从句中作地点状语，其修饰的名词必须是表示地点的名词，如place, factory, house, village等
典型例题：
We’re just trying to teach a point both sides will sit down together and talk. (06’山东卷)
A. where B. that C. when D. which
[解析]先行词a point是表示地点的名词，并在从句中作地点状语，所以用关系副词where来引导，故答案选A。
(2) 关系副词 when引导定语从句时, 只能在定语从句中作时间状语，其修饰的名词必须是表示时间的名词。如time, day, hour, year等
典型例题：
There wastimeI hated to go to school. （04’湖北卷）
A. a; thatB. a; whenC. the; thatD. the; when
[解析]根据题意可知there was a time when......是曾经有段时光......,而且从句中缺少状语，所以选择B。
(3)关系副词why引导定语从句时，只能在定语从句中作原因状语，其修饰的名词必须是表示原因的名词，如reason
e.g. I don’t know the reason why he was absent.
注意：我们在学习的过程中遇到了下面的问题，却不知道如何处理 ：
(1) In an hour, we can travel to places would have taken our ancestors days to reach.
A. where B. when C. which D. what (06’上海卷)
[解析]句中先行词“places”尽管表地点，但在从句作主语，所以答案选C。
(2) Anyway, that evening, I will tell you about later, I ended up staying at Rachel’s place. (04’浙江卷)
A. when B. where C. what D. which
[解析] 此句是非限制性的定语从句,尽管that evening表时间，但在从句中作介词about的宾语，只能用关系代词which ，所以选D。
(3) Is this the reasonat the meeting for his carelessness in his work? (02’上海春季)
A. he explainedB. what he explained
C. how he explainedD. why he explained
[解析]先行词the reason尽管表示“原因”，但在从句中作explained的宾语，这又是个限定性的定语从句，作宾语时可用that或which引导定语从句还可省略，故答案选A。
所以我们得出判断关系代词与关系副词的方法有两种：
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。不及物动词后面无宾语，就必须要求用关系副词或者是介词加关系代词；而及物动词后接宾语，则要求用关系代词。例如：
（1） This is the mountain villageI visited last year.
A. where B. on which C.which D.the one
[解析]此题中的visit是及物动词，需要接宾语，则需要关系代词,所以选择答案C。
（2） I’ll never forget the days I spent in the countryside.
A.when B.whichC.on which D.what
[解析]先行词the days尽管表示“时间”，但在从句中作spend的宾语，缺少宾语应该用关系代词，所以选答案B。
方法二： 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；把先行词放在从句中的谓语动词之后，如果能和动词很连贯的连节在一起，就缺少宾语，先行词就作宾语;如果连不到一起，需要加介词才能很连贯的连接在一起，不缺少宾语，先行词就作状语。例如：
例1. Is this museumyou visited a few days ago?
A. where B. that C. on which D. the one
例2. Is this the museumthe exhibition was held?
A. where B. that C. on which D. the one答案：
[解析]例1选 D，例2 选A
例1变为肯定句：This museum isyou visited a few days ago.例2变为肯定句： This is the museumthe exhibition was held.
在句1中，is后应跟表语，只有the one可以，而后面的you visited a few days ago则做one的定语从句。
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。
考点五：as与which引导的定语从句
as 引导的定语从句，表示说话人对话语的看法、态度、解释或评论。翻译为正如…，像…，与….一致。
e.g. She is very patient, as is known in her work.
Which 引导的定语从句是对主句所叙述的的事情进行补充说明，表明事物的态度或结果。
e.g. The child had a fever every night, which worried his parents very much.
1. as 可以引导限制性定语从句，先行词中有 such, as, so, the same等词修饰, 构成固定搭配:such……as……;as……as……, so……….as……;the same….as…. 同时 as 充当从句的主语、宾语或者表语.
e.g. Such books as you gave me are interesting.
I have the same plan as you.
比较：There are no such writers as you mention. （定语从句）
It gave him such a shock that his face turned white. （结果状语从句）
This is the same book that I lent you yesterday. （the same…that..指同一个）
This is the same book as I lent you yesterday.(the same…as…同样的、同类的，但不是同一个)
2. as 还可以引导非限制性定语从句, 代表指代整个句子的内容, as 从句既可以 放在主句前, 也可以放在主句后.which 也可以引导非限制性定语从句,代表主句的所有内容, 但是 which从句只能放在主句后。
Eg. He is an honest boy, which/as anybody can see.
As we have seen, oceans cover more than 70 percent of the earth.
典型例题
(1)Alice received an invitation from her boss,came as a surprise.
A. it B. that C. which D. he
[解析] 答案选C. 此为非限制性定语从句，不能用 that修饰，而用which，it 和he 都使后句成为句子，两个独立的句子不能单以逗号连接。况且选he句意不通。
（2）The weather turned out to be very good,was more than we could expect.
A. what B. which C. that D. it
[解析] 答案选B。which可代替句子，用于非限制性定语从句，而what不可。that 不能用于非限定性定语从句，it不为连词，使由逗号连接的两个句子并在一起在英语语法上行不通。
3. as 常用在 as often happens, as was pointed out, as was said above, as I remember, as I understand ,as is known, as is reported, as is announced ,as we all known.等结构中。“如……像……” 正如 ……
e.g. Jack has won the first prize, as often happens.
4. 当主从句语意一致时，用as 反之用which.
e.g. She has married again, as we expected.
She has married again, which was unexpected.
Exx.1) .(1998上海) He was very rude to the customs officer, which of course made things even worse.
2).(1999NMET) Carol said the work would be done by October, which personally I doubt very much.
3).(2004北京) As is reported in the newspapers, talks between the two countries are making progress.
4).(2005浙江) As I explained on the phone, your request will be considered at the next meeting.
4. 当主从句语意一致时，用as， 反之用which.
e.g. She has married again, as we expected.
She has married again, which was unexpected.
参考文献
［1］ 魔法英语.中学英语语法大全. 郑州大学出版社.
[2] 新世纪学习宝典.九州图书出版社.
【关键词】定语；关系词；成份；用法
College entrance examination English attributive clause examination site analysis
Yan Xiaomei
【Abstract】The attributive clause is the middle school English teaching key point, is also the difficulty which the student studies, simultaneously is also the hot spot which the college entrance examination examines. But the student presented the fuzzy understanding in the learning process, therefore I unified my teaching experience to make the summary regarding this, by for everybody reference.
【Key words】Attribute; Relational word; Ingredient; Usage
在复合句中，修饰主句中某一名词/代词的从句称为定语从句。被修饰的词称为先行词；引导定语从句的词叫关系词。关系词的作用：1）连接主从句 2）代替先行词在从句中担任成分。所以学习定语从句，可以分三步走：第一找出先行词；第二看先行词在定语从句中的语法功能（做主语、宾语或状语）；第三选择合适的关系词。搞清楚关系词在定语从句中所起的作用是非常关键的。
e.g. He is a student whostudies hard.（在定语从句中作主语）
先行词 关系词 定语从句
关系词的用法：
1）关系代词：who, whom, whose, that, which 在定语从句中作主语、宾语和定语。
who指人,作主语或宾语 (作宾语可省略）
eg: (1) The man who visited our school yesterday is Mr Brown.
(2) The boy （who ）we saw yesterday is Jack.
whom指人,作宾语 (作宾语可省略)
eg:(1) The man（whom）you are going to visit is a famous writer.
(2) Have you met the person （whom）he was speaking about?
whose : 指人或物，作定语，表示 …的。whose从句也可转换为“ the+n.+of +关系代词”型，如：
(1) Harry is the boy whose mother is our Maths teacher.
(2) I saw some trees whose leaves were black.
(3) They live in a house, whose door opens to the south.
→They lived in a house, the door of which open to the south.
→They lived in a house, of which the door opens to the south
which 指物，作主语或宾语 (作宾语可省略)
eg: (1) These are the trees which were planted last year.
(2) This recorder （which） he is using is made in Japan.
(3) Is this the library (which) you borrow books from?
that 指人/物，作主语或宾语 (作宾语可省略）
eg: (1) A plane is a machine that can fly.
(2) He is the man (that) I told you about.
(3) Let’s ask the man that is reading the book over there.
(4) The girl (that) we saw yesterday is Jim’s sister.
(5) The cakes (that) I cooked were delicious.
2）关系副词：当先行词为表示时间，地点，原因的名词，而且在定语从句中作时间，地点和原因状语，用when, where, why .
考点一：关系代词that和which的区别：
1.以下情况，引导词用that，不用which。
1) 先行词为不定代词everything，little，much，all，anything，nothing。或者先行词 被all, much, little, some, any, every, no 等词修饰时;
e.g. Finally, the thief handed everything that he had stolen.
典型例题：
His brother didshe could to help him.
A. all which B. all what C. all D. which
[解析]句中did是及物动词，后缺少宾语，而could后又省略了动词do，所以用all作did的宾语，all后面省略了关系代词that，故答案选C。
2) 先行词前有形容词最高级、序数词修饰时，用that。
e.g. This is the best book (that) I’ve ever read.
3) 先行词被the only（唯一的），the very（正是那个），the last等 修饰时，用that。
e.g. He is the only person that I want to see now.
4) 先行词同时指人和指物时，用that。
e.g. We talked about the things and persons that we saw then.
Do you know the things and persons that they are talking about?
5) 在疑问词who、which、what开头的句子中
eg. Who is the man that is standing over there?
Which of those books that are on the table belong to you?
6) 当先行词在主句中作表语，而关系代词也在从句中作表语时，用that。
eg. Shanghai is no longer the city that it used to be.
Exx.1.This is all I know about the matter.
A. that B. what C. who D. whether
2.Is there anything else you want?
A. which B. thatC. who D. what
3. The last place we visited was the Great Wall.
A. which B. that C. where D. it
4. Please take the second chairis over there.
A. whereB. which C. who D. that
5. Is oxygen the only gashelps fire burn?
A. that B./ C. which D. it
6.Finally, the thief handed everything he had stolen to the police（NMET98’)
A. whichB. whatC. whatever D. that
2. 只用which，不用that的情况：
1）引导非限制性定语从句修饰某物或整个句子时, 不能用that;
e.g. Bruce went towards the fire, which was still smoking.
2）关系代词前有介词前置时,不能用that;
e.g. This is the classroom （that/which）we study in.
This is the classroom in which we study.
Do you remember the day on which you joined our club?
3）一个句子中若有两个定语从句，一个已经用that引导，另一个用which引导；
e.g. He bought a book that could give him much knowledge and which could help him to kill the time.
典型例题：
Her sister has become a lawyer,she wanted to be. (05’湖北卷)
A. whoB. thatC. whatD. which
[解析] 先行词lawyer尽管是人，但这儿表示职业，这是一个非限制性定语从句，关系代词在句中作宾语，只能用which ，不能用that，所以答案选D。
e.g. This is the house in which I lived two years ago.
Do you remember the day on which you joined our
club?
I have got a writing brush with which I can write.
考点二：介词+关系代词
1. 当关系代词作介词宾语，且该介词不是和从句的谓语动词构成固定短语时，介词可以提前，这样就出现“介词+关系代词”。先行词指物，用“介词+which/whose”, 指人则用 “介词+whom/whose”, 且两个关系代词均不能省略，介词的选择要遵循三个原则：
(1) 根据从句中动词与先行词的逻辑关系，
e.g. Is that the newspaper for which you often write articles?
典型例题：
I saw a woman running towards me in the dark. Before I could recognize who she was，she had run back in the direction she had come. (06’重庆卷)A. of which B. by which C. in which D. from which[解析]此题考查由“介词+关系代词”引导的定语从句，根据句意用from which表示“所来的那个方向”，故答案选D。
（2） 根据从句中动词或形容词的习惯搭配，如：
e.g. Can you explain to me how to use theseidioms about which I’m sure.
典型例题：
In the dark street, there wasn’t a single person she could turn for help.
A. that B. who C. from whom D. to whom
[解析] 在此句中，定语从句中缺少宾语，考查介词的选择，根据固定搭配turn to sb for help,所以选择答案D
(3) 根据定语从句表达的意义来确定。
Air, without which man can’t live, is really important.
2. 在非限制性定语从句中，要表示先行词的一部分时，可用“数词/代词 + of + 关系代词”的结构，如：
e.g. There are 50 students in our class, two-thirds of whom have been to Beijing.
典型例题：
There are two buildings, stands nearly a hundred feet high . （04’湖北卷）
A. the larger B. the larger of them C. the larger one that D. the larger of which
[解析] the larger of which指代the larger of the two buildings ，which 在定语从句中指代 building，作介词of的宾语，故答案为D。
注意： 如果定语从句中的介词短语是固定搭配，则介词应放在动词之后，不能拆开放在关系代词前。例如：
e.g:(1) This is the key which you are looking for.
(2) This is the baby whom you will look after.
(3) He is the man who I am looking at.
3. 根据定语从句表达的意义来确定。
Air, without which man can’t live, is really important.
考点三；whose 在从句中作定语，指人或物
whose从句可转换为“of +关系代词”型，即：whose+ n.=the +n.+of which/whom=of which/whom +the + n.
e.g. They live in a house, whose door opens to the south.
They lived in a house, the door of which open to the south.
They lived in a house, of which the door opens to the south.
考点四:考查关系副词where、when与why引导的定语从句
它们相当于“介词+which”，其中where = in/ at +which; when= on/ in /during +which ; why = for+ which
(1)关系副词 where引导定语从句时，只能在定语从句中作地点状语，其修饰的名词必须是表示地点的名词，如place, factory, house, village等
典型例题：
We’re just trying to teach a point both sides will sit down together and talk. (06’山东卷)
A. where B. that C. when D. which
[解析]先行词a point是表示地点的名词，并在从句中作地点状语，所以用关系副词where来引导，故答案选A。
(2) 关系副词 when引导定语从句时, 只能在定语从句中作时间状语，其修饰的名词必须是表示时间的名词。如time, day, hour, year等
典型例题：
There wastimeI hated to go to school. （04’湖北卷）
A. a; thatB. a; whenC. the; thatD. the; when
[解析]根据题意可知there was a time when......是曾经有段时光......,而且从句中缺少状语，所以选择B。
(3)关系副词why引导定语从句时，只能在定语从句中作原因状语，其修饰的名词必须是表示原因的名词，如reason
e.g. I don’t know the reason why he was absent.
注意：我们在学习的过程中遇到了下面的问题，却不知道如何处理 ：
(1) In an hour, we can travel to places would have taken our ancestors days to reach.
A. where B. when C. which D. what (06’上海卷)
[解析]句中先行词“places”尽管表地点，但在从句作主语，所以答案选C。
(2) Anyway, that evening, I will tell you about later, I ended up staying at Rachel’s place. (04’浙江卷)
A. when B. where C. what D. which
[解析] 此句是非限制性的定语从句,尽管that evening表时间，但在从句中作介词about的宾语，只能用关系代词which ，所以选D。
(3) Is this the reasonat the meeting for his carelessness in his work? (02’上海春季)
A. he explainedB. what he explained
C. how he explainedD. why he explained
[解析]先行词the reason尽管表示“原因”，但在从句中作explained的宾语，这又是个限定性的定语从句，作宾语时可用that或which引导定语从句还可省略，故答案选A。
所以我们得出判断关系代词与关系副词的方法有两种：
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。不及物动词后面无宾语，就必须要求用关系副词或者是介词加关系代词；而及物动词后接宾语，则要求用关系代词。例如：
（1） This is the mountain villageI visited last year.
A. where B. on which C.which D.the one
[解析]此题中的visit是及物动词，需要接宾语，则需要关系代词,所以选择答案C。
（2） I’ll never forget the days I spent in the countryside.
A.when B.whichC.on which D.what
[解析]先行词the days尽管表示“时间”，但在从句中作spend的宾语，缺少宾语应该用关系代词，所以选答案B。
方法二： 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；把先行词放在从句中的谓语动词之后，如果能和动词很连贯的连节在一起，就缺少宾语，先行词就作宾语;如果连不到一起，需要加介词才能很连贯的连接在一起，不缺少宾语，先行词就作状语。例如：
例1. Is this museumyou visited a few days ago?
A. where B. that C. on which D. the one
例2. Is this the museumthe exhibition was held?
A. where B. that C. on which D. the one答案：
[解析]例1选 D，例2 选A
例1变为肯定句：This museum isyou visited a few days ago.例2变为肯定句： This is the museumthe exhibition was held.
在句1中，is后应跟表语，只有the one可以，而后面的you visited a few days ago则做one的定语从句。
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。
考点五：as与which引导的定语从句
as 引导的定语从句，表示说话人对话语的看法、态度、解释或评论。翻译为正如…，像…，与….一致。
e.g. She is very patient, as is known in her work.
Which 引导的定语从句是对主句所叙述的的事情进行补充说明，表明事物的态度或结果。
e.g. The child had a fever every night, which worried his parents very much.
1. as 可以引导限制性定语从句，先行词中有 such, as, so, the same等词修饰, 构成固定搭配:such……as……;as……as……, so……….as……;the same….as…. 同时 as 充当从句的主语、宾语或者表语.
e.g. Such books as you gave me are interesting.
I have the same plan as you.
比较：There are no such writers as you mention. （定语从句）
It gave him such a shock that his face turned white. （结果状语从句）
This is the same book that I lent you yesterday. （the same…that..指同一个）
This is the same book as I lent you yesterday.(the same…as…同样的、同类的，但不是同一个)
2. as 还可以引导非限制性定语从句, 代表指代整个句子的内容, as 从句既可以 放在主句前, 也可以放在主句后.which 也可以引导非限制性定语从句,代表主句的所有内容, 但是 which从句只能放在主句后。
Eg. He is an honest boy, which/as anybody can see.
As we have seen, oceans cover more than 70 percent of the earth.
典型例题
(1)Alice received an invitation from her boss,came as a surprise.
A. it B. that C. which D. he
[解析] 答案选C. 此为非限制性定语从句，不能用 that修饰，而用which，it 和he 都使后句成为句子，两个独立的句子不能单以逗号连接。况且选he句意不通。
（2）The weather turned out to be very good,was more than we could expect.
A. what B. which C. that D. it
[解析] 答案选B。which可代替句子，用于非限制性定语从句，而what不可。that 不能用于非限定性定语从句，it不为连词，使由逗号连接的两个句子并在一起在英语语法上行不通。
3. as 常用在 as often happens, as was pointed out, as was said above, as I remember, as I understand ,as is known, as is reported, as is announced ,as we all known.等结构中。“如……像……” 正如 ……
e.g. Jack has won the first prize, as often happens.
4. 当主从句语意一致时，用as 反之用which.
e.g. She has married again, as we expected.
She has married again, which was unexpected.
Exx.1) .(1998上海) He was very rude to the customs officer, which of course made things even worse.
2).(1999NMET) Carol said the work would be done by October, which personally I doubt very much.
3).(2004北京) As is reported in the newspapers, talks between the two countries are making progress.
4).(2005浙江) As I explained on the phone, your request will be considered at the next meeting.
4. 当主从句语意一致时，用as， 反之用which.
e.g. She has married again, as we expected.
She has married again, which was unexpected.
参考文献
［1］ 魔法英语.中学英语语法大全. 郑州大学出版社.
[2] 新世纪学习宝典.九州图书出版社.