第七whenwhileas区别及练习

When while as 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，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 。

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。

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。

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。

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。

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：It' s cold when it snows. 下雪时天冷。

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如：
发生,而是有先后顺序时,一般要用when 。

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。

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、as和when之后均可直接跟一个名词，构成省略句；但是如：As [When]
while 一般不这样用。

a boy, he lived in Japan.他小时候在日本。

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。

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 ________ (watch) TV.
4. Was your father at home yesterday evening? Yes ,he was. He ____ (listen) to the radio.
5. They ____ (not make) a model ship whe n I saw him.
6. ___ they ____ (have) a meeti ng at 4 yesterday afternoon?
No, they ____ . They _____ (clea n) the classroom.
7. ___ it _______ (rain) whe n you left school? Yes, it ______ . (No, it ___ )
8. What ____ your father _____ (do) whe n he was your age?
9. One day, Edis on ___ (wait) for a train to arrive, and sudde nly a little boy ran to the track( 轨
道)to play.
10. He asked me if I ______ (go) fish ing that after noon.
11. The three of them were in a hurry because their pla ne __ (leave) in five mi nu tes.
12. I n a letter, joh n told us that he ___ (come) to china n ext mon th.
13. When the bell ran g, je nny ___ (wait) in her seat.
14. She ____ (make) her dress the whole after noon.
15. While my father ___ (look) through the evening paper, he sudde nly _____ a cry.
16. When I ___ (come) in the room, he ____ (see) me, for he ____ (read) someth ing
17. When we ____ (arrive) at the village, it _____ (get) dark and it _____ (rain) hard.
18. I ___ (know) you _____ (wait) for me here.
19. One day a little mon key __ (play) in a tall tree. A mother crocodile( 鳄鱼) ________ (look) for
food n ear the bank.
20. What ___ your father _____ (do) yesterday evening? He ___ (study) at the evening school.
21. Later his pare nts found that he ____ (sit) on some eggs.
22. When he kno cked at the door, my aunt __ (cook)
23. The stude nts_____ (sing) and ____ (da nee) happily on the playgro und at that time.
24. I ___ (write) a letter whe n the door bell rang.
25. We had no classed at that time. We ___ (pla nt) trees.
二•.改错
1.She is fat but I am thi n.
2.It was rai ning while 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.while
C.so that
D.therefore
2.1 do every sin gle bit of housework ___ my husba nd Bob just does the dishes now and the n.
A.while
B.si nee
C.whe n
D.as
3. __________________________ We were swimmi ng in the lake sudde nly the storm started.
A.whe n
B.while
C.u ntil
D.befor
四.填空：whe n while
1. ____ Margo was talk ing on the pho ne,her sister walked in.
2. ____ we visited the school,the childre n were playi ng games.
3. ____ Sarah was at the barber's,I was going to class.
4. ____ I saw Carlos,he was weari ng a gree n shirt.
5. ____ Alle n was clea ning his room,the pho ne rang.
6. ____ Rita bought her new dog,it was weari ng a little coat.
7. He was driv ing along _____ sudde nly a woma n appeared.
8. ____ Jake was wait ing at the door, an old woma n called to him.
9. He was readi ng a book ___ sudde nly the teleph one rang.
10. ___ it bega n to rain, they were play ing chess.
11. She saw a taxi coming ____ the woma n was wait ing un der the streetlight.
12. ____ the allie n was in the museum,I called the police.
13. The boy was walki ng dow n the street _____ a UFO Ian ded.
14. ____ the alie n was visit ing the museum,the boy called the TV stati on.
15.1 was clea ning my room _____ the fire broke out.
16. ______ Linda shouted his n ame,some people looked at her.。