one/another/the other

one… the other　只有兩個　　　　　　　　
some… the others　 有三個以上
one… another，another…
some… others，others…
others = other people/things
the others = the rest　剩餘的全部
　
1) 泛指另一個用another。
2) 一定範圍內兩人(物)，一個用one，另一個用the other。
3) 一定範圍內三者，一個用one，另一個用one (another)，第三個可用the other，a third。
4) 一定範圍內，除去一部分人/物，剩餘的全部用the others。
5) 泛指別的人或物時，用others當在一定範圍內，除去一部分後，剩餘部分但不是全部時，也用others

Example
He's the one man who can help you out of your difficulty.
他是唯一能幫助你擺脫困境的人。

He drank another glass of beer.
他又喝了一杯啤酒。

Do you have the other ideas?
你有否另外一些意見

Since的四種用法

1) since +過去一個時間點　(如具體的年、月、日期、鐘點、1980, last month, half past six)。
　 I have been here since 1989.
　
2) since +一段時間+ ago
　 I have been here since five months ago.

3) since +從句　
　 Great changes have taken place since you left.
　 Considerable time has elapsed since we have been here.

4) It is +一段時間+ since從句
　 It is two years since I became a postgraduate student.


Ref:http://www.windsn.com/main/grammar/