Question

问什么不能as is known to all that

Answer 1

As is known to us all .是as引导的定语从句，后面是主句，不加that。

如果加that，就会出现这种情况：It is known to us all that the Great Wall is famous .that引导主语从句。

know, know about, know of

这三者都有“知道,了解”的意思。它们的区别是:know 表示直接地知道,熟知；而know of 是间接得知(听人讲过,从书报上看过等); know about指知道关于某事的情况。例如:

I know of him, but I don't know him personally.我听说过他,但不认识他。

It is better to know one thing than to know about ten thousand things.熟知一事要比略知万事要好。

Answer 2

As is known to us all .是as引导的定语从句，后面是主句，不加that。
如果加that，就会出现这种情况：It is known to us all that the Great Wall is famous .that引导主语从句。

Answer 3

As is known to all that……（+句子） 固定搭配
众所周知的是……
As is known to all that language is the carrier of culture. It's full of deepgoingconnotation.
众所周知，语言是文化的载体，具有深刻的文化内涵。