that this these those用法。

单数用 that this 表示 这个 那个
that 还多用于 宾语从句 例如
I know that i am not the man you love
that 还可表示强调句
It is the information that i really want

复数 用 these those
用法较单一

That is a pen .
This is a dog.
These are some pens.
Those are some dogs.