常用when的结构
当主句为过去完成时时,从句为一般过去时,用连词when意思为:当……的时候,……已经发生了
when I heard a man said:“Do you speak English”,I had
nearly reached the town.
当主句为be doing,从句为一般时,常用when.表示当某事发生时,某人正在做某事。
When I got home,he was singing
当主句为be about to do 时,从句为一般时,用when表示某事正要发生时,突然发生了某事。
When he was about to start,I
came in.
2 常用while的结构
当从句为延续性动词或表状态的词,常用while(如为延续性动词,常用be doing) 意为:当……的时候
I came in while he was
singing.
当从句和主句都有be doing时,用while.可理解为当……的时候,同时含有轻微的转折。
While the boy is playing
football,the girl is singing.
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