when所引導從句既可是延續(xù)性的,也可是終止性的.While 所引導的從句,動詞只能是延續(xù)性的.
He was doing his homework,when the telephone rang.
The telephone rang while he was taking a bath.
I’ll phone you again when I get home.
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對比用while.持續(xù)動作,此時從句時態(tài)通常相同.
Would you look after the children while I do the shopping?
While I was playing the piano,my sister was doing her homework.不是什么時態(tài)都可以。要符合以上的中文。when的主要用法：1. 主將從現 I will tell him the news when he comes back.2. 表突然 I was doing my homework when the phone rang.3. 其他都是正常用法。while在中學階段要記住前后動作同時進行?；旧隙际乾F在或過去進行時。如果你是高中，還需掌握while表示雖然和然而的意思。