It’s known to all that..........改成what is known to all is that 中为什么要加is？谢谢

It’s known to all that..........改成what is known to all is that 中为什么要加is？~

前面是it做形式主语，真正的主语是后面的不定式。而后面实际是一个表语从句，what引导一个主语从句，在主语从句中what又作句中的主语，把what引导的主语从句看作一个整体，实际上是一个主语，相当于单数，故用单数。

它和 as is known to all 是相同的意思,都是“众所周知”,而用法上面略有些不同,as is known to all 只可以用在句首或句尾,用“,”隔开.而as it is known to all不仅可以放在句首,还可以后面加“that”从句.而it is known to all 是形式主语的典型,只用于如it is known to all that our teacher is beauful.

It's known to all that ...这是固定句式 “众所周知... (后接一句话)”
what is known to all is that 中 what is known to all 是主语，主语后当然要有个谓语动词，所以就有is.

看：
It is known to all that A loves B.(主语从句)
=That A loves B is known to all.（主语从句）
= What is known to all is that A loves B.（主语从句加表语从句）
=A loves B,which is known to all （定语从句）
= As is known to all, A loves B.（插入语结构）
= A loving B is known to all.（动名词结构）

明白了吗？把它们背出来吧，你会收益的。 顺便问一下，你读几年级？

前一句是it is ......that 从句 后面一句是what is know to all整个为主语，第二个is为整句的谓语that引出is的表语从句

这件事被（人们）所知。
这是被动式
被动式的结构：be+动词过去分词

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巢湖市15599905118： It's known to all是什么意思 - ？
宇印苦参： 这是众所周知的

巢湖市15599905118： It's known to all that.改成what is known to all is that 中为什么要加is?我说的意思是把it换成what,that后为什么要加is - ？
宇印苦参：[答案] 看: It is known to all that A loves B.(主语从句) =That A loves B is known to all.(主语从句) = What is known to all is that A loves B.(主语从句加表语从句) =A loves B,which is known to all (定语从句) = As is known to all,A loves B.(插入语结构...

巢湖市15599905118： It's known to all that reading - ----one's knowledge - ？
宇印苦参：[选项] A. is increasing B. increases C. has increased D. increased

巢湖市15599905118： it known to all还是it is known to all - ？
宇印苦参： 应该是it is known to all(that) 还有其他表达:as everyone knows; as is known to all; Everybody knows ...; it is common knowledge that ...; as we (all)know;as known to all.

巢湖市15599905118： it is known to all that 和as is known to all that 区别 - ？
宇印苦参：[答案] 都表示“众所周知”,但是用法不同It is known to all that the earth is round.it是形式主语;that引导主语从句,是真正都主语As is known to all,the earth is round.中间有逗号,as 引导从句,the earth is round是主...

巢湖市15599905118： it is known to all that后作什么语 - ？
宇印苦参： it 是形式主语, that引导的是主语从句,整体代表真正的主语; 属于强调句型. (1) 陈述句的强调句型:It is/ was + 被强调部分(通常是主语、宾语或状语)+ that/ who(当强调主语且主语指人)+ 其它部分.强调句可以强调除谓语以外的一切成分....

巢湖市15599905118： It's known to all that..........把it换成what,that后面为什么要加上is.各位高手谢谢了 - ？
宇印苦参： 原句it是做形式主语,真正的主语是后面that引导的从句,相当与that...is known to all.it改成What之后,就是What引导的主语从句了,这时that前要加is,变成What is known to all is that...这里that引导第二个系动词is后的表语从句.

巢湖市15599905118： It is known to all放句首it一定要改为as吗? - ？
宇印苦参： 不一定.要看all后面接什么?如果是that引起的一个句话.那 it不能变.如:It is known to all that the earth is round. (众所周知地球是圆的.)

巢湖市15599905118： 如何区别As is known to all与It is known to all?？
宇印苦参： since的语气比because弱,但比as强.since和as引导的从句一般放在句子的开头.since和as的主要区别是:用as引导原因从句语气较弱,所说明原因是附带,而since表示原因暗示着是稍加分析之后才能推断出来原因. 引导原因状语从句的连...

巢湖市15599905118： it known to all和as is known to all有什么区别? - ？
宇印苦参： 因为填it的话就会有两个主句,前面一句,后面一句,这是不符合语法的.填As的话前面一句就是从句,就可以.单独用都没错