When 大家都知道是"当……的时候，"但是很多的情况它不仅仅表示"当……的时候"。我整理了一些在中英翻译过程中经常会遇到的用法如下：
1. 什么时候
1) I don't know when I'll see her again.
我不知道什么时候才能再见到她。
2）I will tell you when to stop.
我会告诉你什么时候停下。
2. 当某事发生时
1）When my door opened I saw a slender man of more than average height with gleaming eyes and a face so striking that it bordered on the beautiful.
我打开房门时，看到的是一个身材瘦长、比普通人略高一点的人，两眼闪着光辉，面貌很引人注意，称得上清秀。
2）We were still standing in the hall when he said: "I want you to meet the children first of hall."
我们还在大厅里站着，这时他忽然说："我想让你先见见孩子们。"
3. 在某事发生后； 一……就……
1） When both visitors had told their stories, he smiled a little, said he would help them find rooms.
两位来客把经历说完后他笑着说，他可以帮他们找到住的地方。
2) When the whale is killed, the blubber is stripped off and boiled down, either on board ship or on shore.
鲸鱼杀死之后， 把鲸脂剥下来熬油，这项工作有的是在船上进行，有的是在岸上进行的。
3）When it is refined into petro it is used to drive the internal combustion engine.
这种油经过提炼变成汽油以后，可以用来开动内燃机。
4. 当某种条件出现时会产生某种状况。
1） Have you ever been at sea in a dense fog, when it seemed as if a tangible white darkness shut you in?
不知你是否有过这样的经历， 在海上航行遇上了大雾，周围一片白，好像着实把你关在一个黑暗的地方。
2） When lead is added to petrol, it improves the car's performance.
铅加在汽油中可以提高汽车的性能。
5. 在…情况下，如果
1） When you are a child of the mountains yourself, you really belong to them.
你如果是在山里长大的孩子，你就对山有感情，你就离不开它。
2） When I finally succeeded in making the letters correctly I was flushed with childish pleasure and pride.
我终于把这几个字母写对了， 这时我天真地感到无限愉快和骄傲。
3) Cattle-raising, long and important industry in Texas, became even more flourishing after the war, when enterprising men began to drive their Texas longhorns north across the open public domain.
在德克萨斯州， 养牛早就是重要事业， 战后尤见繁荣， 大胆的赶牛人赶着德州的长角牛，穿过开放的公共地带，向北走去。
6. 时间状语之后
1） Early one winter, when my uncle's family wanted a new maid, Old Mrs. Wei the go-between brought her along.
有一年冬初， 叔叔家里要换女工，做中人的卫老婆子带她进来。
2） Each morning when I went out to practice singing in the open air, I took a little basket to scrounge for cinders for our stove.
早晨去喊嗓子，我带着一个小篮拾煤核， 为了回家取暖。
3) We had to queue up before dawn when there were still stars in the sky.
每天天不亮戴着星星去排队。
