![](https://cos-cdn.shuashuati.com/pipixue-web/2020-1231-2005-12/ti_inject-812ce.png)
阅读下列程序(控制台程序),程序的输出结果是______________。 public class A { private int speed =10; public int Speed { get { return speed; } set { speed = value; Console.WriteLine(" 禁止驶入 !"); } } } public class B:A { public B() { if(this.Speed>=20) Console.Write (" 机动车 "); else Console.Write (" 非机动车 "); } } class Program { public static void Main() { B b=new B(); b.Speed = 30; } }