第七--when-while-as-区别及练习.

1、Whenwhileas 区别一、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伤了。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，状态延续到从句所指的整个时间，此时通常要用while 。且强调主句动作或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

2、 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。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。二、根据主句与从句动作是否同时发生来区

3、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“一英语一般要用 as (也可用 when)。如：, 就的”意思，The ice cracked as when I stepped onto it.我一踩冰就裂了。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“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：就”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。三、根据是否具有伴随变化来区分若要表示主句动作伴随

4、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。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。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 ：Its cold when it snows.下雪时天冷。

5、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 hell 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。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。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

6、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 mountain s.八、根据所引出的省略句来区分1 、如：as 和when 之后均可直接跟一个名词，构成省略句；但是As When a boy, he lived in Japan. 他小时候在日本。while一般不这样用。2、when 和 wh

7、ile 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。一用所给动词正确行使填空1. I _ (have) my breakfast at half past six yesterday morning.2. Mary _ (go) over her lessons from six to seven last night. John and peter _(do) the same thing.3. What _ you _ (do) at that time? We _ (w

8、atch) TV.4. Was your father at home yesterday evening? Yes ,he was. He _ (listen) to the radio.5. They _(not make) a model ship when I saw him.6. _ they _ (have) a meeting at 4 yesterday afternoon?7. _ it _(rain) when you left school? Yes, it _. (No, it _)8. What _ your father _ (do) when he was you

9、r age?9. One day, Edison _ (wait) for a train to arrive, and suddenly a little boy ran to the track(轨道) to play.10. He asked me if I _ (go) fishing that afternoon.11. The three of them were in a hurry because their plane _ (leave) in five minutes.12. In a letter, john told us that he _ (come) to chi

10、na next month.13. When the bell rang, jenny _ (wait) in her seat.14. She _ (make) her dress the whole afternoon.15. While my father _(look) through the evening paper, he suddenly _ a cry.16. When I _ (come) in the room, he _ (see) me, for he _ (read) something17. When we _ (arrive) at the village, i

11、t _ (get) dark and it _ (rain) hard.18. I _ (know) you _(wait) for me here.19.One day a little monkey _ (play) in a tall tree. A mother crocodile(鳄鱼 ) _ (look) forfood near the bank.20.What _ your father _ (do) yesterday evening? He _(study) at the evening school.21.Later his parents found that he _

12、 (sit) on some eggs.22.When he knocked at the door, my aunt _ (cook)23.The students _ (sing) and _ (dance) happily on the playground at that time.24.I _ (write) a letter when the door bell rang.25.We had no classed at that time. We _ (plant) trees.二 .改错1.She is fat but I am thin.2.It was raining whi

13、le we arrived.3.She sang while he walked.三.选择最佳答案：1.She thought I was praising her child ，_， in fact ，I was scolding him for his bad behaviors at school.A.what B.whileC.so thatD.therefore2.I do every single bit of housework _ my husband Bob just does the dishes now and then.A.whileB.sinceC.whenD.as3

14、.We were swimming in the lake _ suddenly the storm started.A.whenB.whileC.untilD.befor四填空： whenwhile1._ 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 gr

15、een shirt.5._ Allen was cleaning his room,the phone rang.6._ Rita bought her new dog,it was 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 under