Question

that在名词性从句和定语从句中的区别（越

Answer 1

that在名词性从句中不作任何成分，无意义，是个连词，不能省略；定语从句中的that是关系代词，在定语从句中作主语、宾语；作宾语时，可以省略；若介词提前时，不能用that，可以用which或whom。

That he is ill is true.

This is the city (that) you mentioned.

The car that is to be repaired is mine.

I still remember the day on which I joined the army.

that的用法：

一、that 作限定词或代词

that可以作限定词或代词连接名词或名词短语，也可单独使用，用以指代人或者物。此外，that不仅可以指代单独的人或物，还可以指代一句话。

二、that作副词表示程度，相当于so

例：It isn't all that cold. 

天没有那么冷。

Answer 2

that在名词性从句中不作任何成分，无意义，是个连词，不能省略；定语从句中的that是关系代词，在定语从句中作主语、宾语；作宾语时，可以省略；若介词提前时，不能用that，可以用which或whom。
That he is ill is true.
This is the city (that) you mentioned.
The car that is to be repaired is mine.
I still remember the day on which I joined the army.