___is known to us all is that the earth is smaller than the sun.why not use "what".why not use "it"

She is a good woman,___is known to us all. ___is known to us all is that the earth is smaller than the sun.why not use what.why not use it 【英语】选用As 与 it 的一道选择题1.___is well known to us is that many earth's resources are running out.A.It B.What C.As D.Which2..___is well known to us is that getting up early is good for health.A.As B.It C.Which D. What 英语语法,1)--Who is singing in the hall?--___is william.___is known to us all that it is he who sings that way.A.it it b it as c he it d he as2) ____ was 11 o'clock____i finally finished grading the test papers.a it that b it when c that when d t As is known to us.和It is known to us.后面接什么啊?为啥 It Is known to us 和as is known to us 有什么区别 it is known to us all,as is known to us all和what is known to us all有什么区别 ___the emei mountain is famous for its beauty/A as is known to all B it is known to all C it is known to us al that D as we all know thatwhy use C,tell me why and the other why not use them/> it is well known to us that是什么意思 as is known to us that为什么不对呢? lt is known that smoking does great ----[harm]to us. As is known to us 可以怎么造句? As is known to us……和Which is known to us……的区别? As is known to us……和Which is known to us……的区别? 1 ___is known to us all is that the 2008 Olympic Games will take place in beijing.A.It B.What C.As D.Which 3.__ is reported in the newspaper,talks between the two countries are making progress.A.It B.As C.That D.What 高中英语题求解呀~感谢!1： ___is known to us all is that the 2008 Olympic Games will take place in beijing.A.It B.What C.As D.Which 答案：B（怎么不选A呢 如果有that可以选吗?）2:When asked __they needed most,the kids said th ___is very important ___the envioronment around us A this to protect B it to protectC that protecting D it protecting 请问句型It's known to us that从句是被动语态吗?请问句型It's known/well-known to us that从句,是被动语态吗?若是,怎么这里用TO US,不用BY US?