题目内容：

His brother ＿（not do） his homework every day
用适当形式填空

优质解答

His brother doesn't＿（not do） his homework every day.

追问：

原因是什么？

追答：

不好意思，应该是doesn't do，因为这是一般过去时，主语是单三，所以用助动词的否定形式doesn't do。