（1）、抽象类和抽象方法的定义和实现：abstract override

        abstract class Vehicle{

                public abstract void Run();

        }

继承抽象类并且实现抽象方法

        class RaceCar : Vehicle{

                public override void Run(){

                }

        }

（2）、接口的定义和实现：interface

//定义接口类
interface IVehicle
{void Stop();void Fill();void Run();
}//抽象类实现接口类
abstract class Vehicle : IVehicle
{public void Stop(){}public void Fill(){}/*** 抽象类实现接口，保留一个接口放给子类实现的写法*/abstract public void Run();
}class Car : Vehicle
{//子类实现Run方法，注意override关键字public override void Run(){Console.WriteLine("Car is running ...");}
}