it is known to all that 和as is known to all that 区别
问题描述：
it is known to all that 和as is known to all that 区别
答
都表示“众所周知”,但是用法不同
It is known to all that the earth is round.it是形式主语；that引导主语从句,是真正都主语
As is known to all,the earth is round.中间有逗号,as 引导从句,the earth is round是主句