Question

主语从句that 可以省略吗

A person commits an offense if he signs a document he knows is false in any material respect with intent that the document be delivered to the secretary of state for filing.
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从句he（主） signs（谓语） a document（宾语）(he knows is false)括号内 是什么成分

Answer 1

由that引导主语从句不能省略。请看例句：
That he has told lies is quite clear. 他说了谎，这一点很明显。
“That he has told lies”是主语从句，在句中作主语，看作单数，谓语动词用单数。如果省去that，句子就成为：He has told lies is quite clear.句中便有了两个谓语，has told和is，这样就会引起理解上的混乱，显然是错句。
另外，由that引导的主语从句，往往被放在句尾，前面则用it充当形式主语。如：
It goes without saying that he loves her at the first sight. 毫无疑问他对她一见钟情。
It is sheer luck that he survived the accident. 他在事故中逃过一劫纯粹是运气。

Answer 2

主语从句，即在复合句中充当主语成分的句子，例如"That he finished writing the composition in such a short time surprised us all"，他在很短的时间内写完作文让我们都很惊讶，此复合句主要描述的是某事让我们惊讶，某事就是该复合句的主语，因此“That he finished writing the composition in such a short time”便是该复合句的主语从句。
引导主语从句的连词主要有：从属连词：that whether
连接代词：who whoever whom whose what whatever which whichever
连接副词：when where how why
1. It 作形式主语和it引导强调句的比较
①主语从句常用it作形式主语，一般常用句型为：It is+{名词/形容词/过去分词}+主语从句例如：
It is still a question whether she will come or not.
It is strange that you should like him.
It is still unknown which team will win the match.
另外，还有一些比较多见的结构：
It turned out that……;
It has been proved that……;
It happened/occurred that……;
It is well-known that……等等
②而强调句则不同，它的结构是：It+be+被强调部分+that+从句
强调主语：It is the times that produce their heroes.时势造英雄
强调宾语：It is English that Prof.Lin teaches us.
强调状语：It was in shanghai that I saw the film.

Answer 3

名词性从句包括：主语从句；宾语从句；表语从句；同位语从句。that在宾语从句中可以省略；在主语从句、表语从句、同位语从句中不可以省略，起语法上的连接作用。本人英语专业，希望帮助到你