1、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。 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？ 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 ho
2、t（is为延续性动词，表示一种持续的状态）趁热打铁。 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。 When 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。 When I got to the airport，the guests
3、 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。 When 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。 When 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
4、能用 as。这时，as常表示“随着”；“一边，一边”之意。 As the time went on，the weather got worse（as表示“随着”之意） The atmosphere gets thinner and thinner as the height increases 随着高度的增加，大气越来越稀薄。 As 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。 The little girls sang as they went 句子如下： That day, I was doi
5、ng my homework _ my younger brother was watching TV. Suddenly the doorbell rang. A.when B.while C.before D.after when 和while都可以表示“两个动作同时发生”的含义， 此时它们的不同之处在于while 有表示“对比”的含义， 如题目中一人在做作业，一人在看电视，强调两人做不同的事情，有对比的含义,when和while都可以用在多种行为或情况同时发生。具体情况有下面四种： 1.我们经常用when和while引导时间状语从句引出一个大的背景，而在这个背景之下发生发生了主句所描述的
6、行为。 i.e.Somebody broke into the house when/while they were playing cards. 他们在打牌的时候有人闯进了房子。 2.当表示两个长时行为与情况同时发生时，用while而不用when. i.e.While you were reading the paper, I was working.你在读报时，我在工作。 3.when引导的从句表示在主句中描述的大背景下发生了另一行为。这时不能用while. i.e.I was asleep in my chair when Dora rang to say she wasnt comin
7、g home.我睡觉的时候，多利给我打电话说她不会回家。 4.当表示年龄或是生命中的一段时间时，用when而不用while. i.e.When I was a child we lived in London. 我小时候住在伦敦。,讲解三例句： 1. The girls are dancing while the boys are singing. 2. Kangkangs mother is cooking when he gets home. 3. When/While Kangkangs mother is cooking, he gets home.,一、用when或者while填空
8、1._ Margo was talking on the phone, her sister walked in. 2._ we visited the school, the children were playing games. 3._ Sarah was at the barbers, I was going to class. 4._ I saw Carlos, he was wearing a green shirt. 5._ Allen was cleaning his room, the phone rang. 6._ Rita bought her new dog; it w
9、as wearing a little coat. 7. He was driving along _ suddenly a woman appeared. 8. _ Jake was waiting at the door, an old woman called to him. 9. He was reading a book _suddenly the telephone rang. 10. _ it began to rain, they were playing chess.,11. She saw a taxi coming _ the woman was waiting unde
10、r the streetlight. 12. The alien was in the museum, I called the police. 13. The boy was walking down the street a UFO landed. 14. The alien was visiting the museum, the boy called the TV station. 15. I was cleaning my room the fire broke out. 16. Linda shouted his name, some people looked at her.,二
11、、用所给动词适当形式填空 17. While Jake _ (look) for customers, he _ (see) a woman. 18. They _ (play) football on the playground when it _ (begin) to rain. 19. A strange box _ (arrive) while we _ (talk). 20. John _ (sleep) when someone _ (steal) his car. 21. Father still _ (sleep) when I _ (get) up yesterday mo
12、rning. 22. Grandma _ (cook) breakfast while I _ (wash) my face this morning.,23. Mother _ (sweep) the floor when I _ (leave) home. 24. I _ (read) a history book when someone _ (knock) at the door. 25. Mary and Alice are busy _ (do) their homework. 26. The teacher asked us _ (keep) the windows closed
13、. 27. I followed it _ (see) where it was going. 28. The students _ (play) basketball on the playground from 3 to 4 yesterday afternoon.,三、完成下面句子，词数不限 1.飞机在伦敦起飞时正在下雨。 It _ when the plane _ in London. 2.你记得汶川大地震时你在做什么吗？ Do you remember what _ you _ when Wenchuan Earthquake . 3.当铃声想起的时候，我们正在操场上玩得很开心。 W
14、e _ on the playground when the bell . 4.当妈妈下班回家时，你在做什么？ _ when Mum _ from work? 5.当我在做作业时，有人敲门。 _ I was doing my homework, someone _ the door. 6.当外星人正在买纪念品的时候，那个女孩报了警。 _ the alien was buying the souvenirs, the girl _ the police.,答案 1.while 2.when 3.while 4.when 5.while 6.when 7.When 8.While 9.When 1
15、0.When 11.While 12.when 13.when 14.while 15.when 16.when 17.was looking ,saw 18.were playing,began 19.arrived, were talking 20.was sleeping, stole 21.was, sleep, got 22.was cooking, was washing 23.was sweeping,left 24,was reading,knock 25,doing 26.to keep 27. to see 28.were playing 1. was raining, took off 2. were doing ,took place 3. were having fun, rang 4. what were you doing ,came back home 5. while /when, knocked at 6. while, called,Thank U,
