Do you know接从句时后面为什么不加that

1.最后那个句子应该是he said he would go to the ciname tomorrow.would ,用的是过去将来时
2.应该没有说这个句子必须要加that的吧?有资料这么规定的么?
he said that he would go to the ciname tomorrow.=he said he would go to the ciname tomorrow.
主语he 谓语 said that引导出一个宾语从句,这时候引导词that可以省略,也可以保留,而且常见的是它被省略掉的形式,就如这里的 he said he would go to the ciname tomorrow.
3.而问句,是同样的道理,引导词that可以保留可以省略,因为do you know that he will go to the ciname tomorrow?
that引导的是一个宾语从句,这时候that可以省略
4.我们常见的that不能省略的情况是,
1）that引导出一个表语从句
2）that引导出一个主语从句
3）that在定语从句中充当主语成分
5.所以,个人认为,这两个句子,that都是引导宾语从句的,都可以省略,也可以保留
6.do you know 后面加宾语从句时,引导词有好几个
这里 he will go to the ciname tomorrow 是一个成分完整的句子,所以用引导词that
而如果是其他的
do you know why he did such a stupid thing?
do you know where he is?
do you know when it starts?
这类型的,do you know 后面就是加其他的引导词,而这些词在从句中都充当一定的成分的,一般是状语成分,这时候就不能用that了,引导that是引导出一个成分完整的句子的,在里面不充当任何成分,所以可以省略掉