写出程序的输出结果: public class A { public virtual void Fun1(int i) { Console.WriteLine(i) } public void Fun2(A a) { a.Fun1(1) Fun1(5) } } public class B : A { public override void Fun1(int i) { base.Fun1 (i + 1) } public static void Main() { B b = new B() A a = new A() a.Fun2(b) b.Fun2(a) } }