using System;

namespace test
{
    class Program
    {
        class C
        {
            public override string ToString()
            {
                return "C";
            }
        }
        class D : C
        {
            public override string ToString()
            {
                return "D";
            }
        }

        static void Main(string[] args)
        {
            Action<C> actc = ShowC;
            Action<D> actd = actc;
            Console.WriteLine("get "+(actd is Action<C>)); //true

            //Action<C> actc2 = actd; //所以這邊是真的沒救，沒辦法從 Action<D> 轉回 Action<C> 嗎？
            Console.ReadLine();
        }
        private static void ShowC(C c)
        {
            Console.WriteLine(c);
        }
        private static void ShowD(D d)
        {
            Console.WriteLine(d);
        }
    }
}