■ 替代词that与those有何区别
1. that用作替代词主要用于替代“the+单数名词(可数或不可数)”，表特指。如：
A dog’s intelligence is much greater than that of a cat. 狗的智慧比猫的高得多。
A grandparent’s job is easier than that of a parent. 祖父母的任务比父母的任务要轻松一些。
2. those用作替代词主要用于替代复数名词，表特指。如：
It’s up to us to help those in need. 我们有责任帮助那些有困难的人。
It is said that those who eat the most are the least healthy. 据说吃得最多的人身体最差。
Only those who had booked in advance were allowed in. 只有那些预先订票的人可以进去。
■ 替代词that与it有何区别
替代词that与代词it的用法不同，that用于指代前面提到的“同类”事物，而it主要指代前面提到的“同一”事物。如：
The population of
I’m taking a raincoat with me in case I need it. 我随身带有雨衣，以备不时不需。
■ 替代词those与they有何区别
替代词those与代词they用法也不同，those是指代前面提到的“同类”事物，而they (以及宾格them)主要指代前面提到的“同一”事物。如：
Waves of red light are about twice as long as those of blue light. 红色光线的波长约为蓝色波长的两倍。
If the children were to go to the seaside, they would be happy. 如果去海边的话，孩子们会很高兴的。
His books are wonderful. I’ve read every one of them. 他的书写得好极了，我每一本都读过了