as做关系代词的时候,可以代主语,也可以代宾语。
as every one knows这里的as代宾语
as is known to all这里as代主语(或者主句)
例如:
(1) She is late, as is often the
case.
她迟到了,这是经常的事.(先行词是整个主句)
所以这叫做非限制性定语从句
(2) To shut your eyes to facts, as many of you do, is foolish.
对事实视而不见--你们好多人都是如此的愚蠢.(先行词是不定式短语)
这里as many of you do是插入语
应该是插入语,这两种句型一般用在句首,非限定性定语从句一般在句末或句中,经常是which引导的。