小Q科普第一波：when還是while 傻傻分不清楚

when 和while的用法區(qū)別

①when是at or during the time that, 既指時(shí)間點(diǎn)，也可指一段時(shí)間； while是during the time that，只指一段時(shí)間。

因此when引導(dǎo)的時(shí)間狀語(yǔ)從句中的動(dòng)詞可以是終止性動(dòng)詞，也可以是延續(xù)性動(dòng)詞，而while從句中的動(dòng)詞必須是延續(xù)性動(dòng)詞。

②when 說明從句的動(dòng)作和主句的動(dòng)作可以是同時(shí)，也可以是先后發(fā)生；while 則強(qiáng)調(diào)主句的動(dòng)作在從句動(dòng)作的發(fā)生的過程中或主從句兩個(gè)動(dòng)作同時(shí)發(fā)生。

③由when引導(dǎo)的時(shí)間狀語(yǔ)從句，主句用過去進(jìn)行時(shí)，從句應(yīng)用一般過去時(shí)；如果從句和主句的動(dòng)作同時(shí)發(fā)生，兩句都用過去進(jìn)行時(shí)的時(shí)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(shí)，則為： While we were talking, the teacher came in.

b. They were singing while we were dancing.

④when和while 還可作并列連詞。when表示“在那時(shí)”；while表示“而，卻”，表對(duì)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(shí)他們聽到了摩托車的聲音。

b. He is strong while his brother is weak. 他長(zhǎng)得很結(jié)實(shí)，而他弟弟卻很瘦弱。?

【擴(kuò)展】when，while，as引導(dǎo)時(shí)間狀語(yǔ)從句的區(qū)別?

when，while，as顯然都可以引導(dǎo)時(shí)間狀語(yǔ)從句，但用法區(qū)別非常大。

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

①Why do you want a new job when you've got such a good one already？（get為短暫性動(dòng)詞）你已經(jīng)找到如此好的工作，為何還想再找新的？

②Sorry，I was out when you called me．（call為短暫性動(dòng)詞）對(duì)不起，你打電話時(shí)我剛好外出了。

③Strike while the iron is hot．（is為延續(xù)性動(dòng)詞，表示一種持續(xù)的狀態(tài)）趁熱打鐵。

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

二、when從句的謂語(yǔ)動(dòng)詞可以在主句謂語(yǔ)動(dòng)作之前、之后或同時(shí)發(fā)生；while和as從句的謂語(yǔ)動(dòng)作必須是和主句謂語(yǔ)動(dòng)作同時(shí)發(fā)生。

1．從句動(dòng)作在主句動(dòng)作前發(fā)生，只用 when。

①When 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(huì)兒。

②When I got to the airport，the guests had left．（got to后發(fā)生）當(dāng)我趕到飛機(jī)場(chǎng)時(shí)，客人們已經(jīng)離開了。

2．從句動(dòng)作和主句動(dòng)作同時(shí)發(fā)生，且從句動(dòng)作為延續(xù)性動(dòng)詞時(shí)，when，while，as都可使用。

①When ／While ／As we were dancing，a stranger came in．（dance為延續(xù)性動(dòng)詞）當(dāng)我們跳舞時(shí)，一位陌生人走了進(jìn)來(lái)。

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

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

①As the time went on，the weather got worse．（as表示“隨著……”之意）

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

③As years go by，China is getting stronger and richer．隨著時(shí)間一年一年過去，中國(guó)變得越來(lái)越富強(qiáng)了。

④The little girls sang as they went?