it is known to us用在句首时一定要跟that吗?加逗号行不行?

it is known to us用在句首时一定要跟that吗?加逗号行不行? 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 well known to us that是什么意思 it is known to us all,as is known to us all和what is known to us all有什么区别 有关as is known to us all,it is known to us all 的辨析1.As is known to us all,the earth is round.2.It is known to us all that the earthe is round.3.what is known to us all is that the whale is not fish but mammal.请问这3个分别是什么从 It is known to us all_ _ _ _ _there is harm.哪儿有污染 It is known to us that ______（贡献)to the development of computers in our country it known to all还是it is known to all 众所周知,成功源自努力 英语翻译It is known to us all that ___you success. it is known to us all that ……是什么句型? it is known to us all that light.=lt is___ ____that light... 单句改错 It is known to us that reading books widen our knowledge哪里错了? ----is well known to us all that Taiwan belongs to China.--- is known to us all ,Taiwan is part of--is known to us all that Taiwan is part of china---is known to us all is that Taiwan is part of chinaA.it B.As C.That D.what四题应选什么,为什 It's known to us that practice makes perfect.与As is known to us,practice makes perfect!这两个句型到底有何区别? 用定语从句合并两句英文这是原句：It is known to us all that light travels faster than sound. 然后合并成这样形式的：-------------------,light travels faster than sound. 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? as known to us 还是as it is known to us?或者还是as is known to us?as 引导的是什么句子?还有一个问题.几月几日用英语怎么讲?就是写出英语来的那种.听说可以用基数?是不是这样?