在下列句子中，As做非限定性定语从句的主语。
As is the way with these gatherings, the declarations were largely drafted before the delegations arrived.
正如这些集会的方式一样,在各代表团到来之前,这些宣言基本上都被起草了。
As引导非限制性定语从句的主要用法如下：
一、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.
汤姆工作努力,并且乐于助人,这一点我们都知道.
二、非限制性定语从句中的谓语为被动式时,常用as做主语 用于be said，be known，be announced，be reported，be mentioned，be expected，be discussed等。
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 .
众所周知，台湾是中国的一部分。
三、 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.
扩展资料：
1、As可在非限制性定语定语从句中可以做主语或宾语。
例如：
He said he was a king,as was a lie. as代替he was a king做主语
He said he was a king,as we didn't believe. as代替he was a king作宾语.
2、As常见固定用法
as we all know,...做宾语
as everybody knows,...做宾语
as is known to all,...做主语
as is known to the world,...做主语
as has been reported,...做主语
as is said,...做主语
3、由as, which 引导的非限定性定语从句区别
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。
例如：
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。
