that不能省略，句子是不能作主语的。
1、that在句中不做成分。当主语从句位于句首时，不能省略：
That he likes books of this kind is very interesting.= It’s very interesting (that)he likes books of this kind.
这是用的最多的一种主语从句,但把这种主语从句放在句首是很少的,只是为了强调或谓语较长时才这样安排。例如：That prices will go up is certain.
扩展资料
that的其他用法：
当谓语动词是seem、appear、be a pity、be a wonder、be likely等时，使用形式主语It，而将真正的主语放在句尾，这时从属连词that可省略：It appeared to scientists on earth (that) the stars had moved.
a、It +be + 形容词+that从句：It is natural that they should have different views.
b、It +be + 名词 +that 从句：It’s a shame that you’re sick.
c、It + 动词（+ 宾语或状语）+ that 从句：It happened that she wasn’t in that day.
d、It + 动词的被动语态 + that 从句：It’s said that there has been an earthquake in India.
that不能省略，句子是不能作主语的，故用that引导。若去掉则没了主语。
宾语从句中的that可省略.that引导宾语从句无意义，不充当句子成分省略。
单词解析
1、that
英 [ðæt; ðət]；美 [ðæt]
pron. 那；那个
adv. 那么；那样
conj. 因为；以至于
adj. 那；那个
n. (That)人名；(德)塔特
例：They said you particularly wanted to talk to me. Why was that?
他们说你特别想和我谈谈。那是为什么？
例：The story was published in a Sunday newspaper later that week.
这个故事在那周晚些时候被刊登在一家星期日报纸上。
扩展资料
that的用法
1、that用作指示代词的意思是“那,那个”。可指前面提到的那件事,也可指在空间或时间上较另一事物远的事物或人,还可指要表明的或要提及的事物、想法等。
2、that用作关系代词时,指人或事物,同时又在从句中充当句子成分。that偶尔也可引导非限制性定语从句。
3、that还常用以代替who, whom, which,但that...which中的that用做关系代词的先行词。
4、that用作关系代词时在下列情况下可以省略:①引导限制性定语从句在从句中用作宾语时; ②用在there be结构前作主语时; ③用作表语时; ④在定语从句与先行词之间有插入语时;
5、that用作连词时可引导主语从句、宾语从句、表语从句、同位语从句和状语从句。
6、that还常引导间接引语或形容词后面的从句。
7、that在以it作形式主语的句子中或引导宾语从句、状语从句时常可省略。
8、that也可用于表示愿望或遗憾。
本回答被网友采纳例句 That the earth goes round the sun is known to us all.= It is known to us all that the earth goes round the sun,
主语从句多用it做形式主语，但无论是上述的那一种表述，that 都是不可省略的
宾语从句中的that才可省略
.that引导宾语从句无意义，不充当句子成分常省略。但下列情况除外： （1）介词宾语从句的that不省略
（2） and连接的几个从句，第二个从句以后的从句的that不省略。 He told me that he had two sons and that they both had gone to college. （3）在动词+it+宾语补足语+宾语从句结构中，that不省略。 I heard it said that he had gone abroad We found it impossible that he could finish it in such a short time
2.Whether ,if 引导宾语从句：两词可互换，但是下列情形除外：
（1）whether从句中有or not
（2）whether从句做介词宾语 Everything depends on whether you agree with us
3.许多带复合宾语的句子，宾语从句经常移到句子后部，而用it做形式宾语。结构常是： 主语+动词+it+形容词/名词等宾语补足语+宾语从句 We think it wrong that he told a lie to everyone
4.宾语从句的语序要用陈述句语序
False: He is wondering when can he finish this difficult job. Right: He is wondering when he can finish this difficult job.
B 有时候可以用it 作形式宾语，而把真正的宾语从句放在后面。
Bad: I thought that he could finish this job in just two hours impossible.
Good: I thought it impossible that he could finish this job in just two hours.
Bad: He left whether we should continue this project to my judgment. Good: He left it to my judgment whether we should continue this project.
C 带有宾语从句的复合句的否定形式一般是否定主句。
Bad: I think he doesn’t like the English teacher.
Good: I don’t think he likes the English teacher.
D 主句一般过去时态，从句也要用过去时态；具体细节请看第一部分。 False: He wanted to know why he is crying in the corner.
Right: He wanted to know why he was crying in the corner. bu
哪些宾语从句不可以省略引导词that
1当that做learn,suggest,explain,agree,wonder,prove,mean,state,feel,hold等动词的宾语时;
2当宾语从句较长时;
3当主语状语置于主句尾,宾语从句之前时;
4当主语谓语动词(包括非谓语动词)与宾语从句之间有插入语时;
5当一个动词带有两个或两个以上宾语从句时,此时第一个that可以省略,第二个that不可以省略;
6当宾语从句中的主语是this,that或this,that做主语的定语时;
7当宾语从句是双宾语中的直接宾语时;
8当宾语从句的主语是非谓语动词或主语从句时;
9当主语中的谓语动词是固定词组时;
10当宾语从句有it做其先行词时;
11在直接引语中,转述分句把宾语从句隔开时.
主语从句：That he is right is known to all of us.
宾语从句：We all know (that) he is right.本回答被网友采纳