as long as的用法：
1、表示條件，意思是“只要”。如:
As long as you tell the truth，I’ll try to help you.
只要你告訴我實情，我會盡力幫助你。
You may take this book away so long as you return it on time.
只要你按時歸還，就可以把這本書拿走。
2、表示原因，意思是“既然，由于，因為”。如：
As long as we've driven this far, we might as well go on.
我們既然已經駛得這么遠了，就不妨繼續前進。
As long as you are going, I'll go too.
既然你要去，那么我也去。
As long as the weather is changeable these days,we’d better get in wheat in time.
由于這幾天氣候變化無常，我們最好及時把麥收割完。