as和which引导非限制性定语从句的区别

as 和which引导非限制性定语从句的区别
1，as引导的非限制性定语从句，位置灵活，可以置于主句的句首、句中或句末；先行词不可是一个词，必须是整个主句或主句的部分内容；有“正如、像”等意思，表依据、评论（、态度、看法）等；如：
This elephant is like a snake，as anybody can see．像任何人都能看见那样，这头象像条蛇。

He failed in the exam, as we had expected.
Tom has passed the test, as everybody knows. 正如每个人所了解的那样，汤姆通过了考试。

【比较：Bamboo is hollow，which makes it very light．竹子是空的，这就使得它很轻。

】
常用以下谓语动词的主、被动语态：know, see, say, expect, imagine, hope, believe, announce, suggest, report, point out…, 例：
主动（做宾）：as we all know, as you know, as everybody knows; as you see, as we can see, as we have seen, as anybody can see; as was expected; as we can imagine, as we have imagined…
As we all know, the earth is round.
He was a foreigner, as I know from his accent.
Mike, as we expected, attended the meeting．像我们所期望的那样，迈克参加了会议。

被动（做主）：as is known to everybody, as is known to all; as has been expected; as is often the case (with …)，as has been pointed out, as is usual with, as is reported in the newspaper…
He is an honest man, as is known to all.
As is often the case with young people, he was overconfident.
He wasn't unconscious，as could be judged from his eyes．他并未失去知觉，这从他的眼神可以判断出来。

2，which引导非限制性定语从句，只能置于句中或句末（即不可置于句首，只能置于先行词之后）；先行词即可是一个词，也可是整个主句或主句的部分内容；是整个主句时，从句谓语动词用三单。

He seems not to have grasped what I meant, which greatly upsets me. 他似乎没抓住我的意思，这使我心烦。

Liquid water changes to vapor, which is called evaporation. 液态水变为蒸汽，这就叫做蒸发。

He studied hard at school when he was young, which leads to his success in his later life.
有“这、这一点”等意思，表事实、状态、起因、转折、让步等；如：
Bamboo is hollow，which makes it very light．竹子是空的，这就使得它很轻。

Her house, which was built a hundred years ago, stood still in the earthquake. 她的房子尽管是一百多年前建造的，但他在地震过后依然耸立。

（让步）
【比较：He failed in the exam, as we had expected.】
He was late again, which made his teacher very angry. (先行词是一个句子)
He was proud, which I dislike very much.
He was proud, which his brother never was.
She was very patient towards the children, which her husband seldom was.
She was awarded a gold medal, which the whole family considered a great honour.
常用“prep.＋which”结构
They arrived at a farmhouse, in front of which sat a small boy.
He is a library assistant, from whom I borrowed some books.
It is a famous school, from which he graduated 3 years ago.
He is my son, against whom a better son does not exist．
He stood at the window, from which (/ where) he could see what was happening.
There is a tall tree outside, under which (/where) stands our teacher.
用“n./pron./num./adj比较或最高级+ prep.+ which/whom”结构，表示先行词的一部分They talked about a movie, the name of which I've never forgotten．他们谈论过一部电影，我决不会忘记片名。

He paid the boy $10 for washing ten windows, most of which hadn't been cleaned for at least a year.
In Sydney the Chinese team got 28 gold medals，16.5 of which were won by women．在悉尼奥运会，中国队夺得了28枚金牌，其中16．5枚是女子夺得的。

China has a lot of rivers, the second longest of which is the Yellow River.
China has thousands of islands，the largest of which is Taiwan．中国有数千个岛屿，其中最大的是台湾岛。

先行词是独一无二的事物或是专有名词时。

The moon，which doesn't give out light itself，is only a satellite of the earth．月球本身不发光，它只是地球的一个卫星。

Charles Smith, who was my former teacher, retired last year. 查理去年退休了，他曾经是我的老师。

Mr. Zhang, who came to see me yesterday, is an old friend of mine.
Beijing, which has been China's capital for more than 800 years, is rich in cultural and historic relics. 北京是中国八百年之久的古都,它有着丰富的文化和历史遗产。

The Nile，which used to flood every year，now runs more regularly below the dam．尼罗河年年涨洪水，现在比较正常地在大坝下面流过了。

Last year he went to Egypt，which is in Africa．他去年去了埃及，埃及在非洲。

We'll graduate in July, when we will be free. 我们将于七月份毕业，到那时我们就自由了。

先行词被物主代词和指示代词修饰时
My house, which I bought last year, has got a lovely garden. 我去年买的的那幢房子带着个漂亮的花园。

My family，which has 35 people，is a large one．我家有35口人，是一个大家庭。

This novel, which I have read three times, is very touching. 这本小说很动人，我已经读了三遍。

先行词是表人的职业、品质、身份等名词，作定语从句的表语，主从句之间含对比的意思。

Mike's brother is a policeman，which he isn't．迈克的哥哥是警察，他可不是。

Her sister has become a lawyer, which she wanted to be. 她的妹妹成为了一名律师，而这是她曾经的愿望。

在否定意义的非限制性定语从句里（即否定意义的非限制性定语从句不可用as引导。

）Tom has passed the test, which nobody knows. 汤姆通过了考试，但却没人知道。

He came to my birthday party，which I didn't expect at all．他来参加我的生日聚会了，这我完全没有想到。

Li Ling is very clever，which Li Long isn't．李玲很聪明，李珑可不是。

He married her, which was unexpected.
He married her, as /which was natural.
Tom has passed the test, as nobody knows. ( × )
He married her, as was unexpected. ( × )
He came to my birthday party，as I didn't expect at all. 我完全没有想到，他来参加我的生日聚
会。

( ×)
Li Ling is very clever，as Li Long isn't. 李玲很聪明，李珑可不是。

( ×)
互换条件：
非限定从中的as表依据评论，which表事实状态等，但差别不大时可互换。

注意位置：which引导的非限制性定语从句不能置于句首。

例如：
He is quite pleased, as/which can be seen from his face. 他非常高兴，从他的表情可以看出来。

You always work hard, as/which everyone knows. 大家都知道，你一向勤奋学习。

As can be seen from his skin, he must be from Africa.
=He must be from Africa, which/as can be seen from his skin.
As we have seen, oceans cover more than 70 percent of the earth.
=Oceans cover more than 70 percent of the earth, as we have seen.
As you know, Jack is an honest man.
=Jack is an honest man , as you know.
=Jack, as you know, is an honest man.
As is known to all, he is a hero.
=He is a hero, which/as is known to all.
=It is known to all that he is a hero. (that引导的不是定从，而是真主从)
As we all know, smoking is harmful to one's health. (as 作宾语)
=Smoking is harmful to one's health , as we all know. (as 作宾语)
=Smoking, as we all know, is harmful to one' health.
=As is known to all, smoking is harmful to one's health. (as 作主语)
=It's known to all that smoking is harmful to one's health. (that引导的不是定从，而是真主从)。