as is shown in the pictures用法

题目

as is shown in the pictures用法
As shown in the pictures,...
引导图画作文开头的句子.
请问,as is shown in the pictures这部分是一个从句吗?有点像方式状语从句.如果是,为什么没有主语,如果不是,又是什么?改成as we can see in the pictures,...

答案

As 是关系代词,定语从句.
as we can see in the pictures,这里as 还是关系代词