She ____ know the answer ,but I'm not sure .A.maybe B.may

问题描述:

She ____ know the answer ,but I'm not sure .A.maybe B.may
为什么选B不选A,请详解,

A为副词,不是情态动词,故谓语动词需加s,一般maybe反正句首.
may为情态动词,后加动词原形.