mary is play the piano划线提问,一般疑问句,否定回答.划线：the piano
问题描述：
mary is play the piano划线提问,一般疑问句,否定回答.划线：the piano
答
Is Mary playing the piano?
No,she isn't.划线：the piano知道。楼上就是答案。一般疑问句，否定回答，没错。