as is known to..为什么这么用啊?怎么没有了it啊,

as is known to..为什么这么用啊?怎么没有了it啊, As is known to us.和It is known to us.后面接什么啊?为啥 as it is known to all与as is known to all与it is known to all as is known to. as known to us 还是as it is known to us? it is known to us all,as is known to us all和what is known to 如何区别As is known to all与It is known to all? As is known to all 与It is known to all 区别? it is known to all that 和as is known to all that 区别 有关as is known to us all,it is known to us all 的辨析 It's known to us that practice makes perfect.与As is known to it known to all和as is known to all有什么区别?