Is he doing his homework?
No,he isn't.
He isn't doing his homework.
What is he doing?we are washingdishes in the kitchen【washingdishes]一般疑问句，否定句，划线提问，否回Are you washingdishes in the kitchen?No, we aren't.We aren't washingdishes in the kitchen.What are you doing in the kitchen?they taste the apples[the apples]一般疑问句，否定句，划线提问，否回