c#.net中类的覆写(OverRide)

public class MyBase
...{
   public virtual string Meth1()
   ...{
      return "MyBase-Meth1";
   }
   public virtual string Meth2()
   ...{
      return "MyBase-Meth2";
   }
   public virtual string Meth3()
   ...{
      return "MyBase-Meth3";
   }
}

class MyDerived : MyBase
...{
   // Overrides the virtual method Meth1 using the override keyword:
   public override string Meth1()
   ...{
      return "MyDerived-Meth1";
   }
   // Explicitly hide the virtual method Meth2 using the new
   // keyword:
   public new string Meth2()
   ...{
      return "MyDerived-Meth2";
   }
   // Because no keyword is specified in the following declaration
   // a warning will be issued to alert the programmer that
   // the method hides the inherited member MyBase.Meth3():
   public string Meth3()
   ...{
      return "MyDerived-Meth3";
   }

   public static void Main()
   ...{
      MyDerived mD = new MyDerived();
      MyBase mB = (MyBase) mD;

      System.Console.WriteLine(mB.Meth1());
      System.Console.WriteLine(mB.Meth2());
      System.Console.WriteLine(mB.Meth3());
   }
}