在学习线程，遇到个问题，不太清楚.希望各位园友一起讨论解答！一起成长谢谢！

代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;

namespace ThreadDemoConsole
{
    class BankManualResetEvent
    {
        private double account1 = 2500;
        private double account2 = 1000;
        public ManualResetEvent mre = new ManualResetEvent(false);

        public void Transfering()
        {
            mre.Reset();//设置对象mre处于无信号状态
            Console.WriteLine("转账前账户account1还剩余的金额:" + account1.ToString());

            Console.Write("转账金额(元):");
            double sum = double.Parse(Console.ReadLine());
            if (sum > account1)
            {
                Console.WriteLine("转账金额超出了账户account1所剩的金额,转账失败!");
                return;
            }

            account1 = account1 - sum;
            account2 = account2 + sum;
            Console.WriteLine("转账后账户account1还剩余的金额:" + account1.ToString());
            mre.Set();//设置对象mre处于有信号状态
        }

        public void Fetching()
        {
            //阻止当前线程(线程user2)的运行，知道收到对象mre发的信息
            mre.WaitOne();
            Thread.Sleep(100);
            account1 = account1 - 2000;
        }
    }

    class ManualResetEventThread
    {
        static void Main(string[] args)
        {
            BankManualResetEvent a = new BankManualResetEvent();
            Thread user1 = new Thread(new ThreadStart(a.Transfering));
            Thread user2 = new Thread(new ThreadStart(a.Fetching));
            user1.Start();
            user2.Start();
            Console.ReadKey();
        }
    }
}

结果有时是2500，有疑惑