when和while的區(qū)別用法

　　when和while的區(qū)別

　?、賥hen是at or during the time that, 既指時間點,也可指一段時間;

　　while是during the time that,只指一段時間,因此when引導(dǎo)的時間狀語從句中的動詞可以是終止性動詞,也可以是延續(xù)性動詞,而while從句中的動詞必須是延續(xù)性動詞.

　　②由when引導(dǎo)的時間狀語從句,主句用過去進(jìn)行時,從句應(yīng)用一般過去時;如果從句和主句的動作同時發(fā)生,兩句都用過去進(jìn)行時的時候,多用while引導(dǎo),如：

　　a. When the teacher came in, we were talking.

　　當(dāng)此句改變主從句的位置時,則為：

　　While we were talking, the teacher came in.

　　b. They were singing while we were dancing.

　?、踳hen 說明從句的動作和主句的動作可以是同時,也可以是先后發(fā)生;while 則強(qiáng)調(diào)主句的動作在從句動作的發(fā)生的過程中或主從句兩個動作同時發(fā)生.

　?、躻hen和while 還可作并列連詞.when表示“在那時”;while表示“而,卻”,表對照關(guān)系.如：

　　a. The children were running to move the bag of rice when they heard the sound of a motor bike.

　　孩子們正要跑過去搬開那袋米,這時他們聽到了摩托車的聲音.

　　b. He is strong while his brother is weak.

　　他長得很結(jié)實,而他弟弟卻很瘦弱.

　　具體你可以參考這一段.

　　when,while,as引導(dǎo)時間狀語從句的區(qū)別

　　when,while,as顯然都可以引導(dǎo)時間狀語從句,但用法區(qū)別非常大.

　　一、when可以和延續(xù)性動詞連用,也可以和短暫性動詞連用;而while和as只能和延續(xù)性動詞連用.

　?、?Why do you want a new job when youve got such a good one already?(get為短暫性動詞)你已經(jīng)找到如此好的工作,為何還想再找新的?

　?、赟orry,I was out when you called me.(call為短暫性動詞)對不起,你打電話時我剛好外出了.

　?、跾trike while the iron is hot.(is為延續(xù)性動詞,表示一種持續(xù)的狀態(tài))趁熱打鐵.

　　④ The students took notes as they listened.(listen為延續(xù)性動詞)學(xué)生們邊聽課邊做筆記.

　　二、when從句的謂語動詞可以在主句謂語動作之前、之后或同時發(fā)生;while和as從句的謂語動作必須是和主句謂語動作同時發(fā)生.

　　1.從句動作在主句動作前發(fā)生,只用 when.

　?、賅hen he had finished his homework,he took a short rest.(finished先發(fā)生)當(dāng)他完成作業(yè)后,他休息了一會兒.

　?、赪hen I got to the airport,the guests had left.(got to后發(fā)生)當(dāng)我趕到飛機(jī)場時,客人們已經(jīng)離開了.

　　2.從句動作和主句動作同時發(fā)生,且從句動作為延續(xù)性動詞時,when,while,as都可使用.

　?、賅hen /While /As we were dancing,a stranger came in.(dance為延續(xù)性動詞)當(dāng)我們跳舞時,一位陌生人走了進(jìn)來.

　　②When /While /As she was making a phonecall,I was writing a letter.(make為延續(xù)性動詞)當(dāng)她在打電話時,我正在寫信.

　　3.當(dāng)主句、從句動作同時進(jìn)行,從句動作的時間概念淡化,而主要表示主句動作發(fā)生的背景或條件時,只能用 as.這時,as常表示“隨著……”;“一邊……,一邊……”之意.

　?、?As the time went on,the weather got worse.(as表示“隨著……”之意)

　　② The atmosphere gets thinner and thinner as the height increases.隨著高度的增加,大氣越來越稀薄.

　?、跘s years go by,China is getting stronger and richer.隨著時間一年一年過去,中國變得越來越富強(qiáng)了.

　?、躎he little girls sang as they went.小姑娘們一邊走,一邊唱.

　?、軹he sad mother sat on the roadside,shouting as she was crying.傷心的媽媽坐在路邊,邊哭邊叫.

　　4.在將來時從句中,常用when,且從句須用一般時代替將來時.

　?、資ou shall borrow the book when I have finished reading it.在我讀完這本書后,你可以借閱.

　　②When the manager comes here for a visit next week,Ill talk with him about this.下周,經(jīng)理來這參觀時,我會和他談?wù)劥耸?

　　三、when用于表示“一……就……”的句型中(指過去的事情).

　　sb.had hardly(=scarcely) done sth.when...=Hardly / Scarcely had sb.done sth.when...

　　①I had hardly /scarcely closed my eyes when someone knocked at the door.=Hardly / Scarcely had I closed my eyes when someone knocked at the door.我剛一閉上眼,就有人在敲門了.

　?、贗 had hardly /scarcely entered my room when the telephone rang.=Hardly /Scarcely had I entered my room when the telephone rang.我剛一走進(jìn)房門,電話就響了.