when和while的區別

when和while的區別
①when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，所以when引導的時間狀語從句中的動詞能夠是終止性動詞，也能夠是延續性動詞，而while從句中的動詞必須是延續性動詞。
②when 說明從句的動做和主句的動做能夠是同時，也能夠是前後發生；while 則強調主句的動做在從句動做的發生的過程當中或主從句兩個動做同時發生。
③由when引導的時間狀語從句，主句用過去進行時，從句應用通常過去時；若是從句和主句的動做同時發生，兩句都用過去進行時的時候，多用while引導，如：
a. When the teacher came in, we were talking.
當此句改變主從句的位置時，則爲：
While we were talking, the teacher came in.
b. They were singing while we were dancing.
④when和while 還可做並列連詞。when表示「在那時」；while表示「而，卻」，表對照關係。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.
他長得很結實，而他弟弟卻很瘦弱。
具體你能夠參考這一段。
when，while，as引導時間狀語從句的區別
when，while，as顯然均可以引導時間狀語從句，但用法區別很是大。
1、when能夠和延續性動詞連用，也能夠和短暫性動詞連用；而while和as只能和延續性動詞連用。
① Why do you want a new job when youve got such a good one already？（get爲短暫性動詞）你已經找到如此好的工做，爲什麼還想再找新的？
②Sorry，I was out when you called me．（call爲短暫性動詞）對不起，你打電話時我恰好外出了。
③Strike while the iron is hot．（is爲延續性動詞，表示一種持續的狀態）趁熱打鐵。
④ The students took notes as they listened．（listen爲延續性動詞）學生們邊聽課邊作筆記。
2、when從句的謂語動詞能夠在主句謂語動做以前、以後或同時發生；while和as從句的謂語動做必須是和主句謂語動做同時發生。
1．從句動做在主句動做前發生，只用 when。
①When he had finished his homework，he took a short rest．（finished先發生）當他完成做業後，他休息了一下子。
②When I got to the airport，the guests had left．（got to後發生）當我趕到飛機場時，客人們已經離開了。
2．從句動做和主句動做同時發生，且從句動做爲延續性動詞時，when，while，as均可使用。
①When ／While ／As we were dancing，a stranger came in．（dance爲延續性動詞）當咱們跳舞時，一位陌生人走了進來。
②When ／While ／As she was making a phonecall，I was writing a letter．（make爲延續性動詞）當她在打電話時，我正在寫信。
3．當主句、從句動做同時進行，從句動做的時間概念淡化，而主要表示主句動做發生的背景或條件時，只能用 as。這時，as常表示「隨着……」；「一邊……，一邊……」之意。
① As the time went on，the weather got worse．（as表示「隨着……」之意）
② The atmosphere gets thinner and thinner as the height increases．隨着高度的增長，大氣愈來愈稀薄。
③As years go by，China is getting stronger and richer．隨着時間一年一年過去，中國變得愈來愈富強了。
④The little girls sang as they went．小姑娘們一邊走，一邊唱。
⑤The 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．在未來時從句中，經常使用when，且從句須用通常時代替未來時。
①You shall borrow the book when I have finished reading it．在我讀完這本書後，你能夠借閱。
②When the manager comes here for a visit next week，Ill talk with him about this．下週，經理來這參觀時，我會和他談談此事。
3、when用於表示「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。
②I had hardly ／scarcely entered my room when the telephone rang．＝Hardly ／Scarcely had I entered my room when the telephone rang．我剛一走進房門，電話就響了。