C#線程暫停與開啟的代碼

using System;  
using System.ComponentModel;  
using System.Windows.Forms;  
using System.Threading;  
 
namespace AutoResetEventTest  
{  
    public partial class Form1 : Form  
    {  
        private ManualResetEvent manualResetEvent;  
        private AutoResetEvent auto;  
        private bool suspend;  
        private AsyncOperation asyncOperation;  
 
        public delegate void InvokeDelegate(string str);  
 
        private InvokeDelegate invokeDelegate;  
        const string str = "Test";  
        private bool formClosed;  
 
        public Form1()  
        {  
            InitializeComponent();  
            manualResetEvent = new ManualResetEvent(false);  
            auto = new AutoResetEvent(true);  
            asyncOperation = AsyncOperationManager.CreateOperation(null);  
            invokeDelegate = new InvokeDelegate(this.SafeInvoke);  
            this.FormClosed += delegate 
                                   {  
                                       this.formClosed = true;  
                                       this.auto.Close();  
                                   };  
        }  
 
        private void btnStart_Click(object sender, EventArgs e)  
        {  
            this.btnStart.Enabled = false;  
            this.btnSuspend.Enabled = true;  
            ThreadPool.QueueUserWorkItem(delegate 
                                             {  
                                                 SafeInvoke();  
 
                                                 //this.BeginInvoke(invokeDelegate, new object[] { str });  
                                             });  
 &n