//string zuhe 代表的就是片段中的01 03
//需要返回结果就是片段中的15
private string _采集(string zuhe,string url)
        {
            System.Net.WebClient wc = new System.Net.WebClient();
            string data = Encoding.UTF8.GetString(wc.DownloadData(string.Format(url)));
            // 求教中间部分的代码
            return data;
        }

            string str = File.ReadAllText(@"E:\1.txt", Encoding.GetEncoding("gb2312"));
            Regex reg = new Regex(@"(?is)<tr>\s*<td>(.*?)</td>(?:\s*<td>.*?</td>){5}\s*<td>(.*?)</td>.*?</tr>");
            foreach (Match m in reg.Matches(str))
                Console.WriteLine("{0}==={1}", m.Groups[1].Value, m.Groups[2].Value);
/*
01 02===2
01 03===6
02 03===0
01 04===4
*/