as; when与while的用法区别
as; when与while的用法区别
as,when, while作为连词,都有“当……的时候”的意思,它们的区别是
1.as意为“边……边……”或“当…之时”,重在表示动作同时发生或伴随进行。
如:
They talked as they walked.他们边走边谈。
As(when, while)I was doing my homework, he came
当我做作业时,他进来了。
2.when可以指较短的时间,也可以指较长的时间,它所引导的时间状语从句中的动作可以与主句的动作同时发生,也可以是先后发生。从句的动词既可以是终止性动词,也可是持续性动词。如
When I got home, he was having supper.
我到家时,他正在吃晚饭。
When the clock struck ten, all the lights went out.
当钟敲响10点时,灯全部熄了。
3. while常表示一段较长的时间或一个过程,强调主、从句的动词所表示的动作或状态是同时发生的,由它引导的从句中的谓语动词必须是延续性动词,如:
While we were in London. we saw Miss Green twice
在伦敦时,我们见到格林小姐两次
4. while只指“时间段”,不指“时间点”,从句的动词只限于持续性动词
While i slept a thief broke in.在我睡觉时,贼闯了进来。
【注意】①当从句的谓语动词是表动作的延续性动词时,when, while和a才有可能互相替换。如
While / When /As we were still laughing. the teacher came in
正当我们仍在大声嘻笑时,老师进来了。
②从句的谓语动词如果表示状态时,通常用 while。如:
We must strike while the iron is hot.
我们应该趁热打铁。
请选用as; when; while词语的适当形式填空:
)I saw him he was going out of the super market2) Sorry, I was out you called
3)Don' t talk so loud others are working
4) I am weak from hunger, he suffered from having too much food
5) he spoke, they moved forward in their seats.Keys: I)as/when 2)when 3)while 4)While 5)As
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