when和while的用法PPT课件

1、.,1,初中英语微课录制 When和while的用法区别 胡庙一中 刘艳,.,2,一.终止性动词&持续性（延续性和非延续性）动词： 1.概念 2.区别 二.When和while用法的 1.区别 2.举例,.,3,终止性动词&持续性动词的区别,英语中表示动作的动词，按其动作发生过程的长短，可分为持续性动词和终止性动词。,.,4,持续性动词（或称为“延续性动词”）,表示的动作是一种延续的动作，这种动作可以延续下去或者产生持久的影响。,.,5,如：learn，work，stand，lie，know，walk，have等,.,6,终止性动词 （非延续性）,表示的动作不能延续，即动作结束后立即结束，产生

2、某种结果。在有了某种结果之后，动作就不能再继续下去。,.,7,如：marry，close，die，jump，buy，borrow，start等 注：若表示状态和持续性动作时，必须用持续性动词。,.,8,when和while的区别,when是at or during the time that, 既指时间点，也可指一段时间； while是during the time that，只指一段时间，因此when引导的时间状语从句中的动词可以是终止性动词，也可以是延续性动词，而while从句中的动词必须是延续性动词。 when 说明从句的动作和主句的动作可以是同时，也可以是先后发生； while 则强调

3、主句的动作在从句动作的发生的过程中或主从句两个动作同时发生。,.,9,由when引导的时间状语从句，主句用过去进行时，从句应用一般过去时； 如果从句和主句的动作同时发生，两句都用过去进行时的时候，多用while引导，如： a. When the teacher came in, we were talking. 当此句改变主从句的位置时，则为： While we were talking, the teacher came in. b. They were singing while we were dancing.,.,10,when和while 还可作并列连词。 when表示“在那时”；

4、while表示“而，却”，表对照关系。 如： a. The children were running to move the bag of rice when they heard the sound of a motor bike. 孩子们正要跑过去搬开那袋米，这时他们听到了摩托车的声音。 b. He is strong while his brother is weak. 他长得很结实，而他弟弟却很瘦弱。,.,11,When和while引导时间状语从句的区别 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只能和延续性动词连用。 Why do you want a

5、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？ Sorry，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。 Strike 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。 。,.,12,二、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。 When he had

6、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。 When 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都可使用。 When While 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。 When While she was making a phone

7、call，I was writing a letter（make为延续性动词）当她在打电话时，我正在写信。,.,13,3在将来时从句中，常用when，且从句须用一般时代替将来时。 You shall borrow the book when I have finished reading it在我读完这本书后，你可以借阅。 When 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。,.,14,课堂练习,用when，while填空 1. _ the alien

8、 was in the museum , I called the police . 2. The boy was walking down the street _ a UFO landed . 3. _ the alien was visiting the museum , the boy called the TV station . 4. I was cleaning my room _ the fire broke out . 5. _ Linda was shouting his name , some people looked at her . 6. _ Linda final

9、ly saw Davy , he was jumping with a dog .,While,when,While,when,While,When,.,15,When and while意为“当时候”的用法,When 引导的从句表示的动作或状态可以与主句同时发生，也可以先后或紧接发生。,.,16,1. 可以指时间的一点，从句的谓语动词用终止性动词 2. 可以指一段时间，从句用持续性动词。,.,17,For example,1.When I came home, my wife was cooking dinner. 当我回家的时候，我的妻子正在做饭。,.,18,2.The boy was w

10、alking down the street when the UFO landed. 当飞碟着陆的时候，那个男孩正走在街上。,.,19,While,只能指一段时间，从句用持续性动词，不能指时间的一点。其引导的从句表示的动作或状态常与主句同时发生。,.,20,For example,1.While he was, I asked him to lend me 2 yuan. 当他正在吃饭的时候，我请他借给我2元钱。,.,21,2.While the boy was walking down the street, the UFO landed. 当那个男孩走在街上的时候，飞碟着陆了。,.,22

11、,比较 “when” and “while”,when “当.时候”，指时间段或时间点。 后面跟的动作不延续, 常跟一般过去时 When the UFO took off, the boy was taking photos,2.while “当.时候”，指时间段 后面跟的动作延续, 常跟过去进行时 While the boy was taking photos, the UFO took off,Summary the grammar:,.,23,比较 “when” and “while”,2. When the UFO landed, the boy was walkin down the street. While the boy was walking down the street, the UFO landed,1. When the alien got out, the girl was shopping. While the girl