public class person
    {
        public string name { get; set; }
        public int age { get; set; }
        public string address { get; set; }
        public virtual void Say()//基类定义Virtual虚方法
        {

        }
    }

    public class chinese : person
    {
        public override void Say()
        {
            base.Say();
        }
    }

    public class japan : person
    {
        public override void Say()//派生类用override重写基类虚方法
        {
            base.Say();
        }
    }