爱华网浅析as,when和while
作者：俞江涛文章来源《语数外学习》
As,while和when在中学英语里出现很频繁。在高考试题里也多次出现。在它们引导状语从句时，区分它们不是很容易。
难题例释:
（1）-I am going to the post office.
-you're there,can you get me some stamps?
A.AsB.WhileC.BecauseDif答案：B
解析：as,while,because,if都是连词，because引导原因状语从句，容易排除，if引导条件状语从句，也容易排除。干扰项较强的是A。A和B都是引导时间状语从句。根据和用法特点，答案应选B
(2)I was yourage,I had to keep body and soul together by selling newspapers.
A.When; with my parentsdeadB.As; with my parents dead
C.When; with my parentsaliveD.As; with my parents alive 答案：A
解析：I was ourage谈论的是年龄，只能用when。在这里笔者把as,when和while的用法特点进行比较：
1.As,when和while都可表示同时发生的事。例如：
As/When/While I was walking down the street I noticed a policecar in front of number 10.
When/While/As people are learning a foreign language,they shouldnot translate everything
Into their own language.
2.when可表示从句动作与主句动作同时发生，或先于主句动作。while仅仅表示从句的动作与主句同时发生，并且有延续的含义。因此，该从句所用的谓语动词常常是延续性的。
as表示从句动作与主句动作相并发生，所以常常译为“边…边…”，有时也可表示从句动作先于主句动作。
3．从时间上说，when可指一段时间，也可指一点时间：while仅可指一段时间，它引导的从句只能是延续性动词，而不是非延续性动词。as主要是指一段时间，但有时和when一样也指一点时间。例如：
（1）.When Jim arrived,Iwas cooking my supper.(指一点时间，用when。也能用as，但绝不能用 while。)
（2）While the child was playing his toys,his parents werewatchingTV.(主句和从句都指一段时间，只能用while。)
（3）When I got to the theater I found that they had sold allthe tickets.（从句先于主句动作，只能用when.）
4．在下面情况下只能用when:
(1).在表示年龄内容的时间状语从句中。
When Mr Li was already in his fifties,he found it important tostudy English.
（2）在用一般现在时代替一般将来时。一般过去时代替过去将来时的时间状语从句中。
When the plants are in the ground,I'll put some powder on thesoil.
（3）when用在并列分句中，意为then、at thattime。在这种时候，不能用while或as。
I was about to tell him what had happened when the telephonerang.
5．如果主句和从句的主语相同，常常可以省略从句的主语和助动词be,直接跟-ing动词。只能用when和 while，不能用 as。例如：
When/While (I was) driving back home,I saw an accidenthappen.
6.while 的特殊用法：
（1）.I am willing to go, I would like it better thatyou went.
A.BeforeB.AsC.IfDWhile答案：D
解析：含有让步的意思，表示“虽然”相当于although的意思。
(2).I have no money to spend,youhave nothing to spend money on.
A.beforeB.asC.whenD.while答案：D
解析：while表示对比、比较、相对关系，意思为“而、却、反之”。
（3）.you stay with us, we will have a good time.
A.ForB.UntilC.WhileD.As答案：C
解析：While 表示条件，相当于as longas，意为“只要”
（巩固练习）
（）1. (06湖南) I had just stepped out of the bathroom andwas busily drying myself with a towel ______ I heard the steps.
A.whileB.whenC.sinceD. as
() 2. (05浙江) ______ I explained on the phone, your requestwill be considered at the next meeting.
A.WhenB.AfterC.AsD. While
() 3. (04江苏) ______ I accept that he is not perfect, I doactually like the person.
A.WhileB.SinceC.AsD. When
() 4. (04广西) I do every single bit of housework ______ myhusband Bob just does the dishes now and then.
A.sinceB.whileC.when D. as
()5. .(99全国)－－I,m going to the post office.
－－＿＿＿＿＿you're there. can you get me somestamps?
A. AsB.WhileC.WhenD. If
（）6.Theytalkedtheywalked
A.whenB.asC.whileD.since
()7.hecame yesterday, we wre playing basketball.
A.AsB.WhenC.WhileD.If
()8.We muststrikethe iron is hot.
A.whenB.asC.whileD.for
()9.he has finished his work, he takes a short rest.
A.WhenB.whileC.asD.before
()10.Stronghe is,he cannot carry the heavy bag.
A.whenB.asC.whileD.for
参考答案：
1-5BCABB6-10BBCAB
