when 表示短动作,除基本用法外, 还表示突然;while 长动作,另外表对比
adv.（副词）
At what time:
什么时候：
When will we leave?
我们什么时候离开?
conj.（连接词）
At the time that:
在…的时候：
in the spring, when the snow melts.
在春天，当雪融化的时候
As soon as:
一…就…：
I'll call you when I get there.
我一到那里就给你打电话
Whenever:
无论什么时候：
When the wind blows, all the doors rattle.
只要风一吹，这门就吱嘎作响
During the time at which; while:
在…期间，当…时：
When I was young, I was sick all the time.
在我小时候我总是生病
Whereas; although:
虽然，尽管：
She stopped short when she ought to have continued.
尽管她应该继续下去，她却突然停住了
Considering that; if:
考虑到，如果：
How can he get good grades when he won't study?
他不用功的话怎么拿高分呢?
pron.（代词）
What or which time:
什么时候：
Since when has this been going on?
从什么时候起事情象这样?
n.（名词）
The time or date:
时间或日期：
Have they decided the where and when?
他们已经定下来地点和时间了吗?

A period of time:
一段时间：
stay for a while; sang all the while.See Usage Note at awhile
停留下会儿；一直都在唱歌参见 awhile
The time, effort, or trouble taken in doing something:
费时：做一件事情的花费时间、努力或工夫：
The project wasn't worth my while.
这项方案不值得我花工夫，
conj.（连接词）
As long as; during the time that:
只要；在…时间里：
It was lovely while it lasted.
当它开着的时间它是很惹人喜爱的
At the same time that; although:
在…同时；尽管，虽然：
While the grandparents love the children, they are strict with them.
“虽然祖父母们都爱他们的孩子，但却对他们要求严格”
Whereas; and:
然而；而，而且：
The soles are leather, while the uppers are canvas.
鞋跟是皮的，而鞋面是帆布的，
v.tr.（及物动词）
whiled， whil.ing， whiles
To spend (time) idly or pleasantly:
消磨：闲散或轻松地消磨时间：
while the hours away.
消磨时光