when和while的区别
小词汇，大区别。读者朋友们平时在使用when和while是能分清楚什么情况下用while，什么情况下用when么?下面由学习啦小编为你分享when和while的区别的相关内容，希望对大家有所帮助。
when和while有哪些区别
when和while的区别1
1. when引导的时间状语从句中的谓语动词既可以是终止性动词，也可以是延续性动词，而while引导的时间从句中的谓语动词必须是延续性动词。
如：He fell asleep when/ while he was reading. (read是延续性动词)
他看书时睡着了。
It was raining hard when we arrived. (arrive是终止性动词)
我们到达时正下着大雨。
若主、从句表示两个同时进行的持续性动作，且强调主句表示的动作延续到从句所指的整个时间，通常要用 while。
如：Don’t talk while you’re eating. 吃饭时不要说话。
I looked after the baby while her mother was out.她妈妈外出时我照顾她。
Strike while the iron is hot.(is是延续性动词，表示一种持续的状态)
趁热打铁。
2. 在“be about to do…when…”(正要做…，就在这时/突然…) 这个句型中，只能用when。
如：One day, I was about to do some shopping when hetelephoned me.
一天,我正要去买东西,他打电话找我。
3. 在“be on the point of doing…when…” (正要做…，就在这时/突然…) 这个句型中，只能用when。
如：He was on the point of leaving when someone knocked at the door.
他刚要走就有人敲门。
4. 在“be doing …when…” (正在做…就在这时/突然…)这个句型中，只能用when。
如：She was having lunch when an old friend came to visit her.
她正在吃午饭，这时她的一个老朋友来看她。
5. 在“sb had done…when sb did…”(某人刚做完某事，这时/突然…)这个句型中，只能用when。
如：I had just taken a bite of my hot dog when I heard a familiar voice yelling at me from across the crowded school yard.
我刚吃了一口热狗，突然听到在拥挤的校园的那边有个熟悉的声音在喊我。
when和while的区别2
1. 在“sb.had hardly(=scarcely) done sth.when sb. did ...”(一…就…)这个句型中，只能用when。
如：I had hardly /scarcely closed my eyes when someone knocked at the door.
我刚一闭上眼，就有人在敲门了。
2. 上一个句型的倒装形式是“Hardly /Scarcely had sb.done sth.when sb.did...”(一…就…) 这个句型中，只能用when。
如：Hardly / Scarcely had I closed my eyes when someone knocked at the door.
我刚一闭上眼，就有人在敲门了。
3. 引导名词性从句时用when不用while。
如：When she'll be back depends much on the weather.( when 引导主语从句)
她何时回来在很大程度上取决于天气。
4. 引导定语从句的时候用when不用while。
如：Do youremember the time when the three of us wenton a picnic?
你还记得我们三个人去野餐的那段时光吗?
The days are gone forever when the Chinese people were looked down upon.
中国人民被人轻视的日子一去不复返了。
The main school holidays are from mid-December till earlyFebruary，when the days are long and warm.
学校的主要假期是从 12 月中旬到 2 月初，这段时间里白天长而且很温暖。
5. 表示条件，相当于 if ，引导条件状语从句时用when。
如：How can I get a job when I can't even read or write?
如果我连读和写都不会，我怎么能找到工作呢?
6. 引导让步状语从句，意思是“虽然…但是….”、“尽管…但是…”时，用while (多放于句首) 。
如：While he loves his students，he is very strict with them.
虽然他爱他的学生，可是他对他们很严格。
7. 作并列连词用，意思为“而，然而”，表示对比，用while。
如：Some people waste food while others haven't enough.
有些人浪费粮食，然而有些人却吃不饱。
He is strong while his brother is weak.
他长得很结实，而他弟弟却很瘦弱。
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