what are you doing 为什麽be动词要用are

what are you doing,为什么要用are? what are you doing. what you are doing what are you doing What are you doing? 用What are you doing造句 经常在美剧中把What are you doing听成what do you doing.请问是因为口语中省略be动词a what are you doing和what you are doing区别 what are you doing to hello,what are you doing what are you doing here? What are you doing anyway?