题目内容：

as,when,while,的用法
我是中学生

优质解答

1.当从句中的谓语动词是持续性的动作时,我们可以用while,when或as.While / When / As I was walking down the street,I noticed a police car in front of the bank.我顺着马路往前走时,发现银行门前停着一辆警车.2....