一、while 是从属连词，主要表示时间概念，意为“在......时”，跟when 用法相同。例如：

I must finish off this work while the light is good.

趁这会儿光线充足我必须把这项工作完成。

二、此外，while 还可以引导让步状语从句，这时一般放在句首；如果放在句末，则是并列连词，表示对比或转折。分别讲解如下：

（1）while 是从属连词，意为“虽然，尽管”，放在句首：

While the numbers of such developments are relatively small, the potential market is large.

尽管这种增长的数量相对较小，但是潜在的市场是巨大的。

While the modelling business is by no means easy to get into, the good model, male or female, will always be in demand.

尽管模特行业绝不是那么容易进入的，但是好的模特，不论男女，总是需要的。

While the news, so far, has been good, there may be days ahead when it is bad.

尽管到现在为止还都是好消息，但是可能过不了几天就会有坏消息传来。

（2）while 是并列连词，意为“然而，但是”，放在句末：

网友的句子就是该用法。... keeping one eye on the cash register while the other eye is on the microscope.

【翻译】让一只眼睛盯着收银机，而另一只眼睛盯着显微镜。（含义是：科学家不应该既要搞学术研究，又要眼睛盯着钱。）

又如：

Marianne was tempted to turn the large rooms into traditional French-style salons, while Howard was in favour of a typically English look...

玛丽安娜想把这些大房间弄成传统法式客厅的样子，但是霍华德喜欢典型的英式风格。

The first two services are free, while the third costs £35.00.

前两项服务免费，但是第三项服务要花35英镑。

Marianne was tempted to turn the large rooms into traditional French-style salons, while Howard was in favour of a typically English look...

玛丽安娜想把这些大房间弄成传统法式客厅的样子，但是霍华德喜欢典型的英式风格。

The first two services are free, while the third costs £35.00.

前两项服务免费，但是第三项服务要花35英镑。