c# windows窗体的秒表，有3个pc's，它们都不知道为什么一起启动-(编码新手)

using System;
using System.Windows.Forms;
namespace Stopwatch
{
    public partial class StopwatchSpikeForm : Form
    {
        private Timer _timer, _timerB, _timerC;
        private DateTime _startTime = DateTime.MinValue;
        private DateTime _startTimeB = DateTime.MinValue;
        private DateTime _startTimeC = DateTime.MinValue;
        private TimeSpan _currentElapsedTime = TimeSpan.Zero;
        private TimeSpan _currentElapsedTimeB = TimeSpan.Zero;
        private TimeSpan _currentElapsedTimeC = TimeSpan.Zero;
        private TimeSpan _totalElapsedTime = TimeSpan.Zero;
        private TimeSpan _totalElapsedTimeB = TimeSpan.Zero;
        private TimeSpan _totalElapsedTimeC = TimeSpan.Zero;
        private bool _timerRunning = false;
        private bool _timerRunningB = false;
        private bool _timerRunningC = false;
        public StopwatchSpikeForm()
        {
            InitializeComponent();
            _timer = _timerB = _timerC = new Timer();
            _timer.Interval = _timerB.Interval = _timerC.Interval = 1000;
            _timer.Tick += new EventHandler(_timer_Tick);
            _timerB.Tick += new EventHandler(_timerB_Tick);
            _timerC.Tick += new EventHandler(_timerC_Tick);
        }
        void _timer_Tick(object sender, EventArgs e)
        {
            var timeSinceStartTime = DateTime.Now - _startTime;
            timeSinceStartTime = new TimeSpan(timeSinceStartTime.Hours,
                                              timeSinceStartTime.Minutes,
                                              timeSinceStartTime.Seconds);
            _currentElapsedTime = timeSinceStartTime + _totalElapsedTime;
            _totalElapsedTimeDisplay.Text = _currentElapsedTime.ToString();
            _currentElapsedTimeDisplay.Text = timeSinceStartTime.ToString();
        }
        #region PC
        private void startButton_Click(object sender, EventArgs e)
        {
            if (!_timerRunning)
            {
                _startTime = DateTime.Now;
                _totalElapsedTime = _currentElapsedTime;
                _timer.Start();
                _timerRunning = true;
            }
            else
            {
                _timer.Stop();
                _timerRunning = false;
            }
        }
        private void resetButton_Click(object sender, EventArgs e)
        {
            _timer.Stop();
            _timerRunning = false;
            _totalElapsedTime = TimeSpan.Zero;
            _currentElapsedTime = TimeSpan.Zero;
        }
        #endregion
        #region PC-B
        void _timerB_Tick(object sender, EventArgs e)
        {
            var timeSinceStartTimeB = DateTime.Now - _startTimeB;
            timeSinceStartTimeB = new TimeSpan(timeSinceStartTimeB.Hours,
                                              timeSinceStartTimeB.Minutes,
                                              timeSinceStartTimeB.Seconds);
            _currentElapsedTimeB = timeSinceStartTimeB + _totalElapsedTimeB;
            _totalElapsedTimeDisplayB.Text = _currentElapsedTimeB.ToString();
            _currentElapsedTimeDisplayB.Text = timeSinceStartTimeB.ToString();
        }
        private void startButtonB_Click(object sender, EventArgs e)
        {
                if (!_timerRunningB)
                {
                    _startTimeB = DateTime.Now;
                    _totalElapsedTimeB = _currentElapsedTimeB;
                    _timerB.Start();
                    _timerRunningB = true;
                }
                else
                {
                    _timerB.Stop();
                    _timerRunningB = false;
                }
        }
        private void resetButtonB_Click(object sender, EventArgs e)
        {
                _timerB.Stop();
                _timerRunningB = false;
                _totalElapsedTimeB = TimeSpan.Zero;
                _currentElapsedTimeB = TimeSpan.Zero;
        }
        #endregion
        #region PC-C
        void _timerC_Tick(object sender, EventArgs e)
        {
            var timeSinceStartTimeC = DateTime.Now - _startTimeC;
            timeSinceStartTimeC = new TimeSpan(timeSinceStartTimeC.Hours,
                                              timeSinceStartTimeC.Minutes,
                                              timeSinceStartTimeC.Seconds);
            _currentElapsedTimeC = timeSinceStartTimeC + _totalElapsedTimeC;
            _totalElapsedTimeDisplayC.Text = _currentElapsedTimeC.ToString();
            _currentElapsedTimeDisplayC.Text = timeSinceStartTimeC.ToString();
        }
        private void startButtonC_Click(object sender, EventArgs e)
        {
                if (!_timerRunningC)
                {
                    _startTimeC = DateTime.Now;
                    _totalElapsedTimeC = _currentElapsedTimeC;
                    _timerC.Start();
                    _timerRunningC = true;
                }
                else
                {
                    _timerC.Stop();
                    _timerRunningC = false;
                }
        }
        private void resetButtonC_Click(object sender, EventArgs e)
        {
                _timerC.Stop();
                _timerRunningC = false;
                _totalElapsedTimeC = TimeSpan.Zero;
                _currentElapsedTimeC = TimeSpan.Zero;
        }
        #endregion
    }
}