1.引导限制性定语从句和非限制性定语从句
（1）as多与such 或the same连用,可以代替先行词是人或物的名词.
（2）as 也可单独使用,引导非限制性定语从句,作用相当于which.例如：
The elephant’s nose is like a snake,as anybody can see.
（3）the same… that与 the same …as在意思上是不同的.
2．As引导的非限制性定语从句的位置
as引导的非限制性定语从句位置较灵活,可以位于主句前面．中间或后面,一般用逗号与主句隔开,但which所引导的非限制性定语从句只能放在主句之后.例如：
(1) As is expected,the England team won the football match.
(2) The earth runs around the sun,as is known by everyone.
扩展资料
连接词conj.
1. 像...一样；依照；像 例如:You ought to do as Paul tells you. 你应按照保罗吩咐的做。
2. 当...时 例如:As she was leaving the room she remembered that book. 她离开房间时想起了
那本书。
3. 随着 例如:As the sun rose the fog dispersed. 太阳一出来,雾随之消失。
4. 因为 例如:We didn't know what to do as we were just visiting there. 我们不知道该
怎么办，因为当时我们仅仅在那里作访问。
5. 虽然 例如:Tired as he was, he stayed up late. 他虽然疲倦，可仍然很晚才睡。
6.尽管 例如：Try as she might,Sue couldn't get the door open.尽管想尽一切办法，苏还是不能打开那扇门
as用作关系代词和关系副词引导限制性定语从句，并在从句中作主语、宾语、状语或表语，构成the same。
先行词之前一旦出现same, such, so, as这些词时，而先行词的后面又跟着一个从句，这时就要考虑是不是要用as作为关系词来连接这个词和这个句子。
例句：
1. No period in history has had as many important changes ashave taken place in the past century. (as 作主语)
2. It is so easy a book as every schoolboy can read. （as作宾语）
3. A wise man seldom talks about such things as he doesn’t understand.（as作宾语）
4. I shall do it in the same way as you did.（as作状语）
5. Her skin is as white as snow is. (as作表语)
扩展资料:
注意事项:
一:关系代词as在限制性定语从句时，在从句里做宾语时，绝不能省略。
因为很多考生会联想到that和which引导定语从句，做从句里的宾语时可以省略。但是，as引导的定语从句，并且as在定语从句里做宾语时，是绝不能省略的！
例句：
1. Nowadays, women can receive the same pay as men can receive. 这句话里面，as就绝不能省略。
2. Nowadays, women can receive the same pay that men can receive. 里面的that就可以省略。
所以，这句话也可以说成：
Nowadays, women can receive the same pay men can receive.
二.当先行词被 the same 所修饰时，关系词既可以用 as，也可以用 that。不过一般说来，表示同一种类多用 as，表示同一事物多用 that。
例句：
1. This is the same instrument as I used yesterday.
这台仪器跟我昨天用过的那台一样。
2. This is the same instrument that I used yesterday.
这就是我昨天用过的那台仪器。
但是表示抽象概念时，同种类和同一事物是没有绝对区别的，所以as和that两个词可换用。
例句：
I have the same opinion as / that you have.
三:、as引导非限制性定语从句。as在定语从句中作主语、表语或宾语。as代指整个主句，而as引的这个定语从句是用来补充说明整个主句的，可以放在主句之前或者之后。
例句：
1. As we all know, he studies very hard.（as代整个句子，作宾语）
2. He studies very hard, as we all know.
3. As is known to all, he is the best student in our class.（as代整个句子，作主语）
4. He is the best student in our class, as is known to all.
一些常见的句式有：
（1）as is said above, 正如/就像上面所说的
（2） as is already mentioned above, 正如/就像刚才
（3） as在句子里面的意思是“正如”“就像”
四. 关系代词which和as在引导非限制性定语从句时是有区别的。它们的区别就是是：which引导的非限制性定语从句，绝不能放在句首，而as则可以。
1.He studies very hard, as we all know.
2.As we all know, he studies very hard.
而要是换成which的话，
3. He studies very hard, which we all know. 在句中时，as有“正如”“就像”之意，而which则没有此意。
现在看这两句话的区别：
（1） He studies very hard, which we all know.
（2）He studies very hard, as we all know.
尽管as和which都做know的宾语，但是“He studies very hard, which we all know. ”这句话意思是他学习很努力，这点我们都知道。
而“He studies very hard, as we all know.” 这句话意思是他学习很努力，正如大家知道的那样。
参考资料:百度百科——as
本回答被网友采纳AS在定语从句中的用法介绍如下：
一、as用作关系代词和关系副词引导限制性定语从句，并在从句中作主语、宾语、状语或表语，构成the same。
先行词之前一旦出现same, such, so, as这些词时，而先行词的后面又跟着一个从句，这时就要考虑是不是要用as作为关系词来连接这个词和这个句子。
例句：
1、No period in history has had as many important changes ashave taken place in the past century. (as 作主语)
2、It is so easy a book as every schoolboy can read. （as作宾语）
二、as引导非限制性定语从句。as在定语从句中作主语、表语或宾语。as代指整个主句，而as引导的这个定语从句是用来补充说明整个主句的，可以放在主句之前或者之后。
例句：
1、As we all know, he studies very hard.（as代整个句子，作宾语）
2、As is known to all, he is the best student in our class.（as代整个句子，作主语）
扩展资料：
使用时的注意事项：
一、关系代词which和as在引导非限制性定语从句时是有区别的。它们的区别就是是：which引导的非限制性定语从句，绝不能放在句首，而as则可以。
例如：
He studies very hard, as we all know.
也可说：
As we all know, he studies very hard.
而要是换成which的话：
He studies very hard, which we all know. 在句中时，as有“正如”“就像”之意，而which则没有此意。
二、which引导非限制性定语从句作从句里面的介词宾语时，介词可以提到which前面。
例句：
Eric received training in computer for one year, after which he found a job in a big company.
as引导非限制性定语从句作从句里面的宾语时，不能把介词提到as前面的。
本回答被网友采纳1.先行词是all, any, everything, anything, nothing ,something, much, little, few, none ,the one 等时① There is much that should be used.
② You can take any seat that is free.
2.先行词被all, any , no, only, little, much, very, every, some, few, none 等修饰时① I have read all the books (that) you gave me.
② Every dictionary that our library bought is good.
3. 当先行词前有形容词的最高级修饰时① This is the most interesting book that I have ever read.
4. 先行词前有序数词修饰时,包括 the last.① The first lesson that I learned will never be forgotten.
② The Great Wall is the last place that Mr. Smith is going to visit before he leaves Beijing.
5. 在以 which, who作主语的特殊疑问句中的定语从句中① Who is the man that is reading a book there?
② Which is the magazine that you borrowed from the reading room?
6.当先行词既有表示人又有表示物的词时① We talked of the things and persons that we remembered.
7. 当先行词在定语从句中做表语时,无论先行词是人还是物① China is no longer the country that she was.
8.主句以there be 开头时① There is little that I can do to make up for the lost time.本回答被网友采纳
（1）as多与such 或the same连用，可以代替先行词是人或物的名词。
（2）as 也可单独使用，引导非限制性定语从句，作用相当于which。例如：
The elephant’s nose is like a snake, as anybody can see.
（3）the same… that与 the same …as在意思上是不同的。
2．As引导的非限制性定语从句的位置
as引导的非限制性定语从句位置较灵活，可以位于主句前面．中间或后面，一般用逗号与主句隔开，但which所引导的非限制性定语从句只能放在主句之后。例如：
(1) As is expected, the England team won the football match.
(2) The earth runs around the sun, as is known by everyone.
希望对你有用啊！本回答被提问者采纳