請問下列 Java 程式的執行結果為何？ class B { public int ID; public B(int w) { ID=w; } public B() { this(300); } public void speak() { System.out.println("我的編號是" + ID); } } class C extends B { public String name; public C(String n, int w) { super(w); name = n; } public C() { this("小英", 789); } public void speak() { System.out.println("我是" + name); System.out.println("我的編號是" + ID); } } class A { public static void main(String[] args) { B staff1, staff2; staff1 = new C("小明", 543); staff2 = new C(); staff1.speak(); staff2.speak(); } }