what are you doing?中的are為什么不用is?

what nationality are you 中的are 为什么不用is啊 What are you doing?和What is you doing?有什么区别?都是正确的吗? what (is are )you (do doing ) now WHAT IS NEW?HOW ARE YOU DOING? what are you doing 为什么不是is? what are you doing. what you are doing what are you doing What are you doing? What are you doing.baby 什么意思 what are you doing什么意思啊 baby!what are you doing ?什么意思