单词WHEN的详细用法单词WHEN 的详细用法,当它用在过去时时态的时候,比如：when I opened the door……是不是只能在后面跟瞬间动词呢?I was playing soccer when he is doing his homework这样的用法有吗?有无语

单词WHEN的详细用法
单词WHEN 的详细用法,
当它用在过去时时态的时候,比如：when I opened the door……
是不是只能在后面跟瞬间动词呢?I was playing soccer when he is doing his homework这样的用法有吗?有无语法错误,

when,while,as引导时间状语从句的区别
when,while,as显然都可以引导时间状语从句,但用法区别非常大.
一、when可以和延续性动词连用,也可以和短暂性动词连用；而while和as只能和延续性动词连用.
① Why do you want a new job when youve got such a good one already?（get为短暂性动词）你已经找到如此好的工作,为何还想再找新的?
②Sorry,I was out when you called me．（call为短暂性动词）对不起,你打电话时我刚好外出了.
③Strike while the iron is hot．（is为延续性动词,表示一种持续的状态）趁热打铁.
④ The students took notes as they listened．（listen为延续性动词）学生们边听课边做笔记.
二、when从句的谓语动词可以在主句谓语动作之前、之后或同时发生；while和as从句的谓语动作必须是和主句谓语动作同时发生.
1．从句动作在主句动作前发生,只用 when.
①When he had finished his homework,he took a short rest．（finished先发生）当他完成作业后,他休息了一会儿.
②When I got to the airport,the guests had left．（got to后发生）当我赶到飞机场时,客人们已经离开了.
2．从句动作和主句动作同时发生,且从句动作为延续性动词时,when,while,as都可使用.
①When ／While ／As we were dancing,a stranger came in．（dance为延续性动词）当我们跳舞时,一位陌生人走了进来.
②When ／While ／As she was making a phonecall,I was writing a letter．（make为延续性动词）当她在打电话时,我正在写信.
3．当主句、从句动作同时进行,从句动作的时间概念淡化,而主要表示主句动作发生的背景或条件时,只能用 as.这时,as常表示“随着……”；“一边……,一边……”之意.
① As the time went on,the weather got worse．（as表示“随着……”之意）
② The atmosphere gets thinner and thinner as the height increases．随着高度的增加,大气越来越稀薄.
③As years go by,China is getting stronger and richer．随着时间一年一年过去,中国变得越来越富强了.
④The little girls sang as they went．小姑娘们一边走,一边唱.
⑤The sad mother sat on the roadside,shouting as she was crying．伤心的妈妈坐在路边,边哭边叫.
4．在将来时从句中,常用when,且从句须用一般时代替将来时.
①You shall borrow the book when I have finished reading it．在我读完这本书后,你可以借阅.
②When the manager comes here for a visit next week,Ill talk with him about this．下周,经理来这参观时,我会和他谈谈此事.
三、when用于表示“一……就……”的句型中（指过去的事情）.
sb．had hardly（＝scarcely） done sth．when．．．＝Hardly ／ Scarcely had sb．done sth．when．．．
①I had hardly ／scarcely closed my eyes when someone knocked at the door．＝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.
②I had hardly ／scarcely entered my room when the telephone rang．＝Hardly ／Scarcely had I entered my room when the telephone rang．我刚一走进房门,电话就响了.

在高中阶段，when是一个出现频率很高的词，人教版第三册unit 16 Finding Jobs中就有这样的句子：
When they spot young people with talent，they invite them to train with the club.
When David Beckham was a child，he dreamt of playing f...

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在高中阶段，when是一个出现频率很高的词，人教版第三册unit 16 Finding Jobs中就有这样的句子：
When they spot young people with talent，they invite them to train with the club.
When David Beckham was a child，he dreamt of playing for Manchester United.
when可作疑问副词，也可作连接词引导多种从句，在多项语法中都有涉及，也是高考的重点。下文是对when用法的总结。
1.引导特殊疑问句，可译为“什么时候”
When do you think the patient can be operated on？你认为应该什么时候给病人做手术？
2.可引导不定式短语做主语或宾语
Ask him when to open the red wine.问问他什么时候打开红酒.
When to put the new school to use will be announced tonight.新学校什么时候投入使用将在今晚宣布.
3.可引导限定性和非限定性定语从句，修饰主句中表时间的先行词，并在从句中做状语。
There will be one day when the impossible today may become possible.(限定性定语从句)将来会有一天今天不可能的也许会成为可能。
We will put off the picnic until next week，when the weather maybe better.(非限定性定语从句)我们将把野餐推迟到下星期，那时候天气可能会好一些。
4.引导名词性从句
1)引导主语从句
When the foreign friends will arrive is not known yet.外国朋友什么时候到还不知道。
2)引导宾语从句
Lily is asking when she can go back to her hometown again.莉莉问她什么时候可以再回家乡。
3)引导表语从句
That was when I was thirteen.那是我十三岁时候的事了。
4)引导同位语从句
Can you answer the question when Penicillin was discovered？你能回答这和问题吗———盘尼西林是什么时候被发现的？
注意：when引导的主语从句有时会用形式主语it代替When the foreign friends will arrive is not known yet.=It is not known yet when the foreign friends will arrive.
5.引导时间状语从句，可译为“当…时候”，本文开始课文句子中的when即为此用法。
When he got up，he felt dizzy.当起身时他感到头晕。
When he looked back，the woman had disappeared.当他回头看时，那个女人已消失踪迹了。
6.when引导从句的特例：
1)表示突然发生某事或紧接着发生某事，常可译为“…还没/刚刚…就…”，“…正在…忽然…”或“正要…这时…”，主要用于“had done…when…，be doing…when…和be about to do…when…”这三个句式
I had hardly opened the door when the man hit me.我刚打开门，那个人就打了我一拳。
I was reading a book attentively when an old friend came to see me.我正在全神贯注地读一本书，忽然一位老友来访。
I was about to swim in the river when the guide told me there was man-eating fish in it.我正要下河游泳这时导游告诉我河里有食人鱼。
2)表示对比，常可译为“本该/本可以…却…”
Why are you here when you should be at school？你本应在上学，怎么会在这儿？
Why did you take a taxi when you could walk here within five minutes？你本来五分钟就可以走到这儿，为什么还打的？
3)表示让步，常可译为“既然”或“在…情况下”
How can they learn anything when they spend all their time watching TV？既然他们把所有的时间都花在了看电视上，又怎么会学到东西呢？

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当抽象时间被划线提问时,是以WHEN做疑问词,,后面这句应该是when he is doing his homework,I played soccer.可能会错，但应该是这样的

副词 adv. 什么时候，何时
at what time
· When can you come to see me?
你什么时候来看我？
· When did you go to bed last night?
昨晚你什么时候睡觉的？
· When are you going to return it?
你准备什么时候还（书）...

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副词 adv. 什么时候，何时
at what time
· When can you come to see me?
你什么时候来看我？
· When did you go to bed last night?
昨晚你什么时候睡觉的？
· When are you going to return it?
你准备什么时候还（书）？
副词 adv. 是…时候
at which;on which
· Please tell me when we'll have the meeting.
请告诉我我们什么时候开会。
· I wonder when that was.
我不知道那是什么时候的事。
副词 adv. 在…的时候
at or during which
· How I regretted the days when I had played and should have studied!
我多么懊悔我本该好好学习却玩掉了的那么多的日子！
副词 adv. 那时
but at that moment
· It happened on a day in November when the weather was very wet and cold.
这事发生在十一月的一天，那时天气又潮湿又寒冷。
· We were about to start,when it began to rain.
我们刚要出发时开始下雨了。
连词 conj. 当…时
at the time when
· It happened when I was living in the country.
这事发生在我住在农村的时候。
· It was raining when we arrived.
我们到达时，天正下着雨。
· He always comes on those days when I am busy.
他总在我忙的日子来。
· I was walking along the stream,when I met my teacher of English.
当我沿着小溪散步时遇到了英语老师。
连词 conj. 一…就
immediately after
· When I had finished dinner I went to bed.
我吃完饭就睡觉了。
· She was very surprised when she saw me.
她见到我非常惊讶。
· Let us set out when the sun has risen.
太阳一出来，我们就动身。
代词 pron. （关系代词）那时
which time
· I came here in 1949, since when I have been engaged in this work.
我1949年到这里，从那时起我就担任这项工作。
· We came a week ago,since when the weather has been bad.
我们在一星期前来此，从那时起天气就一直不好。
代词 pron. （疑问代词）什么时候
what time
· Since when have you been here?
你从何时起在此地？
· Until when can you stay?
你能呆到什么时候？

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