one, 前面无其它限定语时，替代“同类事物中的（不同的）一个”：

e.g. She has an English book and I have one, too. = ...and I have an English book,too.

the ...one, 很少用，不够明确，一般要明确的限定语：the red/ small/ black/ larger + one, etc.

加了合适的限定语后：特指。也指同类事物中的特定的一个，避免重复前面提到的名词。

Of the three apples, I want the smallest/largest one =apple. 避免再说：the smallest apple.

that

1. 替代前面提到的相同的不可数名词：

The weather in Beijing is colder than that (= the weather) in Shanghai in winter.

2. 替代单数可数名词，功能= it, 指同一个事物，即前后所指是“原物”。

I lost my English dictionary some days ago. I still haven't found it/ that= the dictionary.

3. 指代前面描述的整个事件或情形。

Steve Jobs passed away too early. That/ It maked Apple fans extremely sad.

that/it = the situation that Steve Jobs passed away too early.

these， 永远不可以做替代词！

those (things/ people), = the ones，指代同类事物或人群中的另一群/组，复数：

The students in Class 1 are more hardworking than those in Class 2.

those = the students in Class 2. 都是学生，但是不同班级的学生。

The books in this shop are cheaper than those (books) in that shop.

those = the books in that shop. 都是书，但是不同的书。