题目内容：

His brother is reading a story book 对reading a story book 提问

优质解答

reading a story book是doing sth.对动词提问用what,然后再把be动词提前,其余的照着写下来.所以,这个疑问句应这样变:
What is his brother doing
因为reading是用的动词+ing形式,所以要用doing.