__is know to everybody that Russia is the biggest country in the world.空上为什么填 It 不填 As

问题描述:

__is know to everybody that Russia is the biggest country in the world.
空上为什么填 It 不填 As

it is known that ....意为“据大家所知”
as is known可以理解为“正如大家所知道的那样”
从意思上可以作出区分

It is know to everybody-------句子已经完整
that
Russia is the biggest country in the world.------句子完整
that引导的同位语从句 指代it形式主语。
As is know to everybody , Russia is the biggest country in the world
在这里 as是介词,有 正如.... 的意思。

it在此只是个形式主语,真正的主语是 that Russia is the biggest country in the world
as则没有代词的功能