when/while 辨析When Aunt Huang came back,I was so tired.
黄阿姨回来时，我累极了。The young American stood quietly while the British grards searched his clothes.
当英国卫兵搜查他的衣服时，这位年轻的美国人神色自若地站着。
<辨析>这两个词都可用作从属连词，表示时间，意思都是“当（在）......的时候”，但有所区别：when 的含义是 at or during the time that，既可用于指时间的一点（从句的谓语动词需用终止性动词），也可用于指一段时间（从句的谓语动词用延续性的动词），从句与主句里面的谓语动作或状态能同时发生或紧接着发生，也可能一先一后分别发生。如：He wants to help people when they are ill.
他想在人们生病的时候帮助他们。When he heard this,the Genie changed again into smoke.
妖怪一听这话，就又变成了烟。When he reached Shanghai,the ship had already set off.
他到达上海时，轮船已经开走了。
while 的含义是 during the time that，只能用于指一段时间（从句的谓语动词必须是延续性的），从句与主句里面的谓语动作只能表示同时发生，不能表示先后分别发生。如：One day while they were working in the fields,some farmers was something strange in the sky.
有一天，一些农民在田间劳动的时候，发现空中有个奇怪的东西。While I was reading,my mother was washing clothes.
我读书时，我妈妈在洗衣服。这两个词还可用作并列连词。when 是“在那时”或“这时突然”(and just at that time)的意思，用来连接两个并列分词，有时 when 分句之前有逗号把前后两句分开。如：An Arab was walking along through the desert when he met two men.
有个阿拉伯人正独自在沙漠里行走，这时他碰见了两个人。I stayed till sunset,when it began to rain.
我一真待到太阳下山，那时天开始下雨。while 意为“而”，“却”，表示对照关系。如：Instead,he saked his father why he was not able to hatch chickens while hens could.
他反而问他父亲，为什么他不能孵出小鸡，而母鸡却能孵出小鸡。
张老师 2021-01-30
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