为什么我不能声明C＃方法虚拟和静态？

I have a helper class that is just a bunch of static methods and would like to subclass the helper class. Some behavior is unique depending on the subclass so I would like to call a virtual method from the base class, but since all the methods are static I can't create a plain virtual method (need object reference in order to access virtual method). I have a helper class that is just a bunch of s