這三個詞 據(jù)我所知沒有時態(tài)用法的區(qū)別
1.when 是指某個時間所發(fā)生的事,用于在完成時態(tài)
while是指某個時間段所發(fā)生的事,用于進(jìn)行時態(tài)
2.①when意為"在……時刻或時期",它可兼指"時間點(diǎn)"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.
②while只指"時間段",不指"時間點(diǎn)",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(jìn)來.
③when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.
④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)栽诖舐曟倚r,老師進(jìn)來了.
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.
⑦while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.
while可以表示對比 如
i like coffee while Tom like milk.
as與when,while都是引導(dǎo)時間狀語從句的從屬連詞,含義都是"當(dāng)……的時候".但它們有區(qū)別：用when時,從句的動作可以與主句的動作同時發(fā)生,也可以先于主句的動作發(fā)生；用while時,從句的動作為一過程,主句動作與從句動作同時進(jìn)行或在從句動作過程中發(fā)生；用as時,主句和從句的動作同時發(fā)生,具有延續(xù)的含義.例如：
(1)It was raining when he got to the airport.他到達(dá)工地時,天正在下雪.
(2)someone knocked at the door while paul‘s mother was cooking.有人敲門的時候保羅的母親正在做飯.
(3) You will grow wiser as you grow older.你會隨著年齡的增長而越來越聰明