【W(wǎng)hen與while 的區(qū)別與聯(lián)系】
一、when意為"在……時刻或時期",它可兼指"時間點"與"時間段",所引導(dǎo)的從句的動詞既可以是終止性動詞,也可是持續(xù)性動詞.如：
When I got home,he was having supper.我到家時,他正在吃飯.
When I was young,I liked dancing.我年輕時喜歡跳舞.
二、while只指"時間段",不指"時間點",從句的動詞只限于持續(xù)性動詞.如：
While I slept,a thief broke in.在我睡覺時,盜賊闖了進來.
三、【辨析】
1、when從句與主句動作先后發(fā)生時,不能與while互換.如：
When he has finished his work,he takes a short rest.每當(dāng)他做完工作后,總要稍稍休息一下.(when = after)
When I got to the cinema,the film had already begun.當(dāng)我到電影院時,電影已經(jīng)開始了.(when=before)
2.when從句動詞為終止性動詞時,不能由while替換.如：
When he came yesterday,we were playing basketball.昨天他來時,我們正在打籃球.
3.當(dāng)從句的謂語是表動作的延續(xù)性動詞時,when,while才有可能互相替代.如：
While / When we were still laughing,the teacher came in.正當(dāng)我們?nèi)栽?大 聲嬉笑時,老師進來了.
4.【另外,when和while的區(qū)別還在于：while引導(dǎo)的時間狀語從句多用進行時 態(tài),而when引導(dǎo)時間狀語從句,主句用過去進行時,從句應(yīng)用一般過去時.
例如：1>、While they were talking ,the bell rang.
正在他們談話的時候,上課鈴響了.
2>.When the teacher come in,we were talking.【當(dāng)此句改變主從句的位置時,應(yīng)該用While we were talking ,the teacher come in.我們正談話的時候,老師進來了.（這是一個復(fù)合句.其中while we were talking 是由while引導(dǎo)的時間狀語從句.這里while表示主句的動作是發(fā)生在從句所表示的時間之中.顯然,while 所表示的是一段時間,不是表示一點時間.）
【試比較：
（1）、They were sweeping the floor when the teacher came in.
老師進來時（這一時刻）,他們在擦地板.
（2）、While they were sweeping the floor,the teacher came in.
他們正擦地板時（這段時間）,老師進來了.】
(3) I was doing my homework when my mother came back home yesterday evening.昨天晚上媽媽回家的時候,我正在做家庭作業(yè).】
【注意】：如果主句和從句的動作同時發(fā)生,兩句都用過去進行時的時候,多 用while引導(dǎo).例如：They were singing while we were dancing.】
5.當(dāng)從句的謂語動詞是終止性動詞,而且主句的謂語動詞也是終止性動詞時,when可和as通用,而且用as比用when在時間上更為緊湊,有"正當(dāng)這時"的含義.如：
He came just as (or when) I reached the door.我剛到門那兒,他就來了.
6.從句的謂語動詞如表示狀態(tài)時,通常用while.如：
We must strike while the iron is hot.我們應(yīng)該趁熱打鐵.
7.while和when都可以用作并列連詞.
Mike is tall while his brother is short.邁克的個子很高,然而他弟弟很矮.
Mary was on her way home when two big boys stopped her.瑪麗正走在回家的路上,這時兩個大個子男孩攔住她.
【【W(wǎng)hen與while 】】
1.while后面跟 時間段,when后面可跟 時間點 或 時間段(一般跟時間點).
2.while中主句和從句的 動作 必 同時發(fā)生,when中主句和從句 動作 可以是 同時發(fā)生,也可以是 不同時發(fā)生.
3.while中謂語動詞必用延續(xù)性動詞,when中可用延續(xù)性或瞬間性.
4.while可表示轉(zhuǎn)折,when不行.