面试题002（继承&重写）

 public class Test2A
    {
        int i = 1;
        public virtual void M1()
        {
            Console.WriteLine("i am A");
        }
        public void M2()
        {
            Console.WriteLine("i = {0}",i);
        }
    }

    public class Test2B : Test2A
    {
        int i = 2;
        public override void M1()
        {
            Console.WriteLine("i am b");
        }

        public void M2()
        {
            Console.WriteLine("i = {0}", i);
        }
    }

   Test2B b = new Test2B();
   Test2A a = b;
   a.M1();   //M1被重写了，b的M1方法
   a.M2();  //调用为a的M2方法 
   b.M1();   
   b.M2();