程序由兩部分組成，如下代碼所示。第一部分定義了委托、類和事件。第二部分進行驗證。?

using System;
namespace HelloWorldApplication 
{ public delegate void DelegateRing();public class Bell{ public event DelegateRing Ring;public void OnRing(){ Ring(); } } / 請填寫代碼 / class HelloWorld { static void Main(string[] args) { try{ Teacher teacher = new Teacher(); teacher.Register(new Bell()); Student student = new Student(); student.Register(new Bell()); Console.ReadKey(); } catch(Exception ex) { Console.WriteLine(ex.Message); } } } 
}

只需要輸出樣例輸出的結果

只需要提交需要填寫的代碼

    public class Teacher{public void Register(Bell bell){Console.WriteLine("teacher");}    }public class Student{public void Register(Bell bell){Console.WriteLine("student");}}

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