abstract class Square : TemplateClass   //爸爸级
    {
        public Square(string shape, double length)
            : base(shape, length)
        {
                //显式调用基类的构造方法
        }
        protected override void Length(double length)
        {
            double squareLength;
            squareLength = 4 * length;

            Console.WriteLine
                ("边长为{0}的正方形周长 = {1}", length, squareLength);
        }
        protected override void Area(double length)
        {
            double area;
            area = Math.Pow(length, 2);

            Console.WriteLine
                ("边长为{0}的正方形面积 = {1}", length, area);
        }
        public void GetResult()
        {
            Length(length);
            Area(length);
            Volume(length);
            
        }
       abstract protected void Volume(double length)   //定义一个抽象方法
        {
            //定义方法
        }
    }


//错误提示：“抽象类2.Square.Volume(double)”无法声明主体，因为它标记为 abstract