what are you doing,为什么要用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? what are you doing 为什么不是is? what are you doing now?为什么要+now啊 What are you doing为什么要加ing 英语为什么要What are you doing?而不是What do you doing?我经常把are和do 弄混 用What are you doing造句 what are you doing 为什么不说What IS your name? what are you doing for vacation?为什么要用for不用on