as是這個從句的主語,as是關係代詞,你可以把as換成which就明白了,但是有的情況下,先行詞需要用as而不用which。一般指代的是後面的事(或前面的)。
1,as 能放在定語從句句首
和固定用法搭配:as you know.
如例句:
As is known to all, China is a developing country.
as在定語從句中是關係代詞,可做句子成分.
as 引導非限制性定語從句,可放在主句之前,或者主句之後,甚至可以切割一個主句另外, as有“正如……,正像……”的意思,如:
As is known to all, China is a developing country.