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高中英语重点词语辨析:when,while,as区别详解

2016-11-13 17:39:12 来源:佚名
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  高中英语重点词语辨析:when,while,as区别详解


  一、根据从句动作的持续性来区分


  1.“主短从长”型:即主句是一个短暂性的动作,而从句是一个持续性动作,此时三者都可用。如:


  Jim hurt his arm while[when,as]he was playing tennis.吉姆打网球时把手臂扭了。


  As[When,While]she was waiting for the train,she became very impatient.她在等火车时,变得很不耐烦。


  注意:as用于引出一个持续性动词表示“在……期间”时,其谓语通常只能是那些含有动作(action)和发展(development)意味的动词,一般不能是那些不用于进行时态的动词(如be,seem,love,want,agree,see,know,have等),所以下面一句中的while不能换为as:


  A:I'm going to the post office.我要去邮局。


  B:While you are there,can you get me some stamps?当你在邮局时,能帮我买几张邮票吗?


  2.“主长从长”型:即主句和从句为两个同时进行的动作或存在的状态,且强调主句动作或状态延续到从句所指的整个时间,此时通常要用while。如:


  I always listen to the radio while I'm driving.我总是一边开车一边听收音机。


  He didn't ask me in;he kept me standing at the door while he read the message.他没有让我进去,他只顾看那张条子,让我站在门口等着。


  但是,若主句和从句所表示的两个同时进行的动作含有“一边……一边”之意时,则习惯上要用as。如:


  He swung his arms as he walked.他走路时摆动着手臂。


  I couldn't remember a story to tell the children,so I made one up as I went along.我想不出有什么故事可给孩子讲了,只好现编现讲。


  3.“主长从短”型:即主句是一个持续性动作,而从句是一个短暂性动作,此时可以用as或when,但不能用while。如:


  It was raining hard when[as]we arrived.我们到达时正下着大雨。


  When[As]he came in,I was listening to the radio.他进来时,我在听收音机。


  二、根据主句与从句动作是否同时发生来区分


  1.若主句与从句表示的是两个同时发生的短暂性动作,含有类似汉语“一……就”的意思,英语一般要用as(也可用when)。如:


  The ice cracked as[when]I stepped onto it.我一踩冰就裂了。


  He jumped to his feet as the boss came in.老板一进来他立刻站了起来。


  但是,在hardly[scarcely]…when…句式中,不能将when换成as。如:


  Scarcely had we arrived,when it began to rain.我们刚一到就下起雨来了。


  2.若主句与从句表示的是两个几乎同时发生的短暂性动作,含有类似汉语“刚要……就”“正要……却”的意思,英语一般要用as(也可用when),且此时通常连用副词just。如:


  I caught him just when[as]he was leaving the building.他正要离开大楼的时候,我把他截住了。


  Just as[when]the two men were leaving,a message arrived.就在这两个人要离开的时候,突然有了消息。


  三、根据是否具有伴随变化来区分


  若要表示主句动作伴随从句动作同时发展变化,有类似汉语“随着”的意思,英语习惯上要用as,而不用when或while。如:


  The room grew colder as the fire burnt down.随着炉火逐渐减弱,房间越来越冷。


  As time goes by my memory seems to get worse.随着时间的流逝,我的记忆力似乎越来越差。


  注:若不是引导从句,而是引出一个短语,则用with,不用as。如:


  With winter coming on,it's time to buy warm clothes.随着冬天到来,该买暖和衣裳了。


  The shadows lengthened with the approach of sunset.随着太阳下落,影子也逐渐伸长。


  四、根据从句动作的规律性来区分


  若暗示一种规律性,表示“每当……的时候”,英语一般要用when。如:


  It's cold when it snows.下雪时天冷。


  He smiles when you praise him.你夸奖他时他总是笑笑。


  五、根据主从句动作的先后顺序来区分


  若主句与从句所表示的动作不是同时发生,而是有先后顺序时,一般要用when。如:


  When he arrives he'll tell us all about the match.等他到了,他会好好给我们讲讲那场比赛的情况。


  When she had finished she waited as though for a reply.她讲完之后等了等,仿佛是在等候回答似的。


  六、根据是否具有“趁机”意味来区分


  1.若从句所表示的“当……的时候”具有“趁机”的意味,则通常用while。如:


  Strike while the iron is hot.趁热打铁。


  I tried to slip the note to him while the teacher wasn't looking.我想趁老师不注意时把条子偷偷递给他。


  有时也用when。如:


  He stole the money when no one was by.他趁旁边无人时把钱偷走了。


  The boy looks at her repeatedly when she's not looking.那男孩趁她没看他的时候不断地盯着她看。


  七、根据是否用作并列连词来区分


  when可用作并列连词,表示“这时(突然)”;while也可以用作并列连词,表示“而”“却”(表示对比);但as则没有类似用法。如:


  I was just about to go to bed when I heard a knock on the door.我正要睡觉,听见有人敲门。


  One person may like to spend his vacation at the seashore,while another may prefer the mountains.一个人会喜欢在海滨度假,而另一个人会喜欢在山里度假。


  八、根据所引出的省略句来区分


  1.as和when之后均可直接跟一个名词,构成省略句;但是while一般不这样用。如:


  As[When]a boy,he lived in Japan.他小时候在日本。


  As[When]still a student,he wrote a novel.当他还是个孩子的时候,他就写了一本小说。


  2.when和while之后可接现在分词、介词短语、形容词等构成省略句,但as一般不这样用。如:


  When[While]reading,he fell asleep.他看书时睡着了。


  When[While]in trouble,ask her for help.遇到麻烦的时候你就去找她帮忙。


  You must study hard while(you are)young,or you will regret when(you are)old.你趁年轻时必须努力学习,不然到老了你会后悔的。

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