StreamReader sr = new StreamReader("data.txt");

 private   void run_Click(object sender, EventArgs e)
        {
            url = Uurl.Text.ToString();
            num = 0;
             if(url.Contains(@"http://"))
             {
                 url=url.Replace(@"http://","");
             }

            myThread  = new Thread(new ThreadStart(runSEO));
             this.run.Enabled = false;
             myThread.Start();
           
        

        }

        public   void runSEO()
        {
            try
            {
               
                while ((urlhead = sr.ReadLine()) != null)
                {

                    num = num + 1;
                    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(urlhead + url);
                    request.Timeout = 1000;
                    HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            
               
               
                }
                sr.Close();
                run.Invoke(btnchange);
               
            }
            catch
            {
             
                run.Invoke(btnchange);
            }
        }

如果请求的网址超时，为什么我的线程是直接停止而不是跳过这个网址继续request下一个呢？怎样让它在请求一个网址不成功就跳过继续下一个？