How many books does she have?

问题描述:

How many books does she have?
为什么要用does而不用do?解释一下
前面不是books吗

she是第三人称单数、故用does
像it、he、she、还有类似、MARY、HER MOTHER等都用does
do是 I WE THEY、用的.
do和does是根据主语来决定的.