does she have book? 为什么不是does she has abook?

题目

does she have book? 为什么不是does she has abook?
还有has she a book ?怎么回答?
还有has she a book ？怎么回答？

答案

因为前面的 does 已经是第三人称单数 所以 这里不能再用has