He has a bad cold,Mr.Williams,so he must stay in bed for a weekso he must stay in bed for a week其中的stay为什么不加S

问题描述:

He has a bad cold,Mr.Williams,so he must stay in bed for a week
so he must stay in bed for a week其中的stay为什么不加S

must是情态动词~所以后面接的动词都用原型!没有特例!