as在定语从句中的用法，要详细点的解释

Answer 1

定语从句中，一般的从句关系代词是which、who、whom、that、 whose, 其代替主句中的人或物，在从句中做主语、宾语或定语。而学生在学习过程中，常会遇到as作为关系代词出现，做起题来，无从下手,就此笔者对as作为关系代词引导定语从句的情况做一归纳, 以供参考.

一、as引导限制性定语从句

主要结构有：

the same…as

as…as

such…as

so…as

主句中出现the same, as, such, so修饰先行词，需选择as做关系代词在定语从句中做主语或宾语。

1. It’s the same person as we wanted to find yesterday .

我们昨天要找的是同一个人。

2. Such girls as he knows are good at English .

他所认识的女孩都擅长英语。

3. Do you have such books as we like ?

你有我们喜欢那种书吗？

4. She will marry as healthy a man as she can find .

她将嫁给她能找到的任何一个有钱人。

5. There is so warm a house as we want to live in .

这里有如此暖和的房子，我们都想住在里面。

6. He has so difficult a problem , as none of us can solve .

他有如此难的一个问题，我们没有人能解决。

二、引导非限制性定语从句

⑴ as引导非限制性定语从句，指代整个主句内容，从句可置于句首，句中或句尾

1． As everyone knows ,China is a beautiful country with a long history .

每个人都知道，中国是一个有着悠久历史的美丽国家。

2． The earth , as we know , moves round the sun .

地球，我们都知道，围着太阳转。

3． Tom works hard and is willing to help others, as we all know.

汤母工作努力，并且乐于助人，这一点我们都知道。

⑵ 非限制性定语从句中的谓语为被动式时，常用as做主语

be said/known/announced/reported/mentioned/expected/discussed

1. Grammar , as has been said before, is not a set of dead rules.

语法，就像以前所说，不是一套死规则。

2. As is known to all , TaiWan is part of China .

⑶ as引导非限制性定语从句，有“如，似，正像”的含义，因此，下列句式多用as

as has been said above

如上所说

as anybody can see

正像每个人所看到的那样

as we had expected

正如我们所预料的那样

1. Things are not always as they appear.

事情并不一直像他们表面那样。

2. The boy has as much progress as we had expected.

正像我们所预料的那样，这个男孩取得了大的进步。

由as, which 引导的非限定性定语从句，as和which可代整个主句，相当于and this或and that。As一般放在句首，which在句中。
As we know, smoking is harmful to one';s health.
The sun heats the earth, which is very important to us.
as 和which在引导非限制性定语从句时，这两个关系代词都指主句所表达的整个意思，且在定语从句中都可以作主语和宾语。但不同之处主要有两点：
(1） as 引导的定语从句可置于句首，而which不可。
(2） as 代表前面的整个主句并在从句中作主语时，从句中的谓语必须是系动词；若为行为动词，则从句中的关系代词只能用which.。

Answer 2

as 引导限制性定从时其先行词必由so ,such,as ,the same所修饰
as 引导非限制性定从 译成“正如，正像” 句首的非限定从必由as引出
例如 She is so good a girl as we all like .限制性定从
As we all know, China is very great. 非限制性定从

Answer 3

AS在定语从句中的用法：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.