【帮忙看看代码】关于事件的题目

Question

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;namespace 事件_基本使用_
{
    public class Person
    {
        private int _currentBp=120;
        private int _maxBp;
        public Person(int maxBp)
        {
            this._maxBp = maxBp;
        } 
        public event callEventHandler callEvent;
        public void increaseBp()
        {
            this._currentBp += 5;
            if (this._currentBp > this._maxBp)
            {
                if (this.callEvent != null)
                    this.callEvent(); //为什么一直是null
            }
        }
      
    }    public delegate void callEventHandler();    public class Wife
    {
        private Person _person;
        public Wife(Person person)
        {
            this._person = person;
            this._person.callEvent+=new callEventHandler( this.savHusband);
        }
        public void savHusband()
        {
            Console.WriteLine("夫人救丈夫中");  
        }
    }    public class Stranger
    {
        private Person _person;
        public Stranger(Person person)
        {
            this._person = person;
            this._person.callEvent+=new callEventHandler( this.call120);
        }
        public void call120()
        {
            Console.WriteLine("Call 120");
        }
    }
}
 static void Main(string[] args)
        {
            SaveHusband();
            Console.ReadKey();
        }
 static void SaveHusband()
        {
            Person person = new Person(130);
            person.increaseBp();
            person.increaseBp();
            person.increaseBp();
           
            Wife wife = new Wife(person);
            Stranger stranger = new Stranger(person);
             
        }
刚复习事件，然后做了这题，
思路是，先定义事件的委托，
        然后在类的内部定义事件，
        然后在一定条件下触发事件
        最后调试。
不知道哪里错了，大家帮忙看看。

Answer 1

哎，没事了，解决了，static void SaveHusband()
        {
            Person person = new Person(130);
            person.increaseBp();
            person.increaseBp();
            person.increaseBp();
           
            Wife wife = new Wife(person);
            Stranger stranger = new Stranger(person);
             
        }这里应该改成static void SaveHusband()
        {
            Person person = new Person(130);
             Wife wife = new Wife(person);
            Stranger stranger = new Stranger(person);
            person.increaseBp();
            person.increaseBp();
            person.increaseBp();
           
           
             
        }太大意了

Answer 2

static void SaveHusband()
{
    Person person = new Person(130);
    
    Wife wife = new Wife(person);
    Stranger stranger = new Stranger(person);
   
    person.increaseBp();
    person.increaseBp();
    person.increaseBp();
}
这个函数里面内容有问题， 得先实例前面的对象，再改变条件满足触发条件 。

Answer 3

把涉及 Stranger的部分去掉是好的