这也是今天讨论的话题。取消是默认就支持的，而暂停则默认不支持。但通过ManualResetEvent可以对其进行干预。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Threading;namespace BackgroundWorkderPauseSample
{public partial class MainForm : Form{BackgroundWorker worker = null;public MainForm(){InitializeComponent();Load += new EventHandler(Form1_Load);}void Form1_Load(object sender, EventArgs e){worker = new BackgroundWorker();worker.WorkerReportsProgress = true;worker.WorkerSupportsCancellation = true;worker.DoWork += new DoWorkEventHandler(worker_DoWork);worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);}void worker_ProgressChanged(object sender, ProgressChangedEventArgs e){progressBar1.Value = e.ProgressPercentage;}void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e){if (e.Cancelled)MessageBox.Show("用户取消了操作");else{MessageBox.Show("正常完成了操作");}}void worker_DoWork(object sender, DoWorkEventArgs e){for (int i = 0; i < 100; i++){if (worker.CancellationPending)//如果用户申请取消{for (int k = i; k >= 0; k--){Thread.Sleep(10);worker.ReportProgress(k);//模拟一个回滚的效果}e.Cancel = true;return;}manualReset.WaitOne();//如果ManualResetEvent的初始化为终止状态（true），那么该方法将一直工作，直到收到Reset信号。然后，直到收到Set信号，就继续工作。//反之亦然Thread.Sleep(500);worker.ReportProgress(i+1);}}private void btStart_Click(object sender, EventArgs e){worker.RunWorkerAsync();}private void btCancel_Click(object sender, EventArgs e){worker.CancelAsync();}private ManualResetEvent manualReset = new ManualResetEvent(true);private void btPause_Click(object sender, EventArgs e){if (btPause.Text == "暂停"){manualReset.Reset();//暂停当前线程的工作，发信号给waitOne方法，阻塞btPause.Text = "继续";}else{manualReset.Set();//继续某个线程的工作btPause.Text = "暂停";}}}
}
这个程序运行的效果大致如下

一。正常状态

二。暂停状态

三。恢复状态

作为演示，代码比较简单，没有对worker的一些状态进行判断以及按钮相应的设置。仅供参考