//CannotchangesourcecodeclassBase{publicvirtualvoidSay(){Console.WriteLine("CalledfromBase.");}}//CannotchangesourcecodeclassDerived:Base{publicoverridevoidSay(){Console.WriteLine("CalledfromDerived.");base.Say();}}classSpecialDerived:Derived{publicoverridevoidSay(){Console.WriteLine("Calledfrom
