that
①远指：指代距离说话者较远的单数对象（人或事物）,对应复数是those.例如：
That is my book.Those are theirs.
②用于比较结构,以保持比较对象相同.经常指代不可数对象,属于【同类同物】,相当于
【the+不可数名词】.例如：
Ms Shen's mothod of teaching is nothing like 【that】of the teachers at my junior high school.
that=the method of teaching
this
与that第一用法相对,用以表示近指,即指代距离说话者较近的单数对象,对应复数是these.
例如：
This is his pen.These are ours.
one 不定代词,表泛指,指代不确定的单数可数对象,属于【同类异物】,相当于【a/an+单数名词】.其复数是ones,特指形式是the one(复数 the ones).
例如：
Meeting my uncle after all these years is an unforgetting moment,【one 】that I will never forget.
it
作为代词,表示特指,属于【同名同物】,指代上文所提到的同一个对象.例如：
I have an interesting book,and【 it 】is a story book.
I have a bike.It is given by my father as a birthday gift.
祝你开心如意!