为什么是What were you doing,是过去式为什么要用doing,不是what were you do

为什么是What were you doing,是过去式为什么要用doing,不是what were you do what were you doing 为什么是were不是what what were you doing? Do you remember what you were doing? 你在做什么用英语说为什么是what are you doing 不是what do you doing啊 what did you do 与what were you doing What were you doing at 7:30 last night? 请问do为什么加ing do you remember what you were doing?不可以用do you remenber what 复述Do you remember what you were doing? Do you remember what you were doing 英语复述 Do you remember what you were doing?中的知识点 Do you remember what you were doing?知识点汇总