指特定的两个人或物中的“一个.另一个时”,只能用one...the other,故此为具体范围内；
指不确定范围中的人或物中的“一个.另一个时”,用one...another,在大范围下
如：
1.I have two brothers.One is a lawyer and the other is a
manager.(两兄弟中的一个.另一个)
2.I've got two tickets.One is for you and the other is for
myself.
3.He finished one cup of tea and then asked for another cup.
4.Since you don't like this one,I'll show you another.