using system;
namespace Conversion_Example
{
  class Program
  {
   static void Main(string[] args)
   {
       Teacher t = new Teacher();
       Human h = t ; //把T这个变量所存的地址赋给了H
       /*当你拿一个引用变量去访问它所引用着的实例的成员的时候，只能访问到变量的类型所具有的成员，而不是这个变量所引用的实例的类型。所以H这个变量只有eat和think，没有teach, h.teach根本不存在*/
    
    }
  }

   class Animal
   {
      public void Eat()
      {
      console.writeline("Eating.....");
     }
   }

  class Huamn:Animal
   {
      public void Think()
      {
      console.writeline("Who i am.....");
     }
   }

  class Teacher:Human
   {
      public void Teach()
      {
      console.writeline("i teach programming....");
     }
   }

}

using system;
namespace Conversion_Example
{
  class Program
  {
   static void Main(string[] args)
   {
     Stone stone = new Stone();
     stone.age    = 5000;
     Monkey wukongsun = (Monkey) stone;
     Console.Writeling(wukongsun.age);
    
    }
  }

   class Stone
   {
      public int age();

      public static explicit operator Monkey(Stone stone)
      {
       Monkey m = new Monkey();
       m.age       = stone.age/500;
       return m;
       }


      
   }

  class Monkey
   {
      public int age;
   }



}