POST求助 抓包都正常 cookie每次都一样 不变

您好，
//准备cookie
04.
05.CookieContainer cookie = new CookieContainer();
06.
07.string[] strcookie = "BAIDUID=9ABC673457A0DB3B19F801E3CE7B8976:FG=1; _EXPS=0; cflag=65535%3A1; NEW_NAV_TIME=2; H_PS_PSSID=3146_1424_3138_2785_2980_3092_2701; IM_old=0|hknp852y; _BDSC=1; BDUSS=80VkFoalNYTnVsbXQ0ZG5jNXJXNTF4SU8wZXg5M2pXd2hqQ3ZuTWtlSk9WRDFTQVFBQUFBJCQAAAAAAAAAAAEAAACIMZY2ampqamp4anh4AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAE7HFVJOxxVSNk".Split();
08.
09.foreach (string co in strcookie)
10.
11.{
12.
13.cookie.SetCookies(new Uri("http://cang.baidu.com/do/cm"), co);
14.
15.}
16.
17.
18.
19.//开始post
20.
21.HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
22.
23.request.Method = "POST";
24.
25.request.Host = "www.baidu.com";
26.
27.request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
28.
29.request.ContentType = "application/x-www-form-urlencoded; charset=UTF-8";
30.
31.request.ContentLength = Encoding.UTF8.GetByteCount(postDataStr);
32.
33.request.CookieContainer = cookie;
34.
35.request.Referer = "http://www.baidu.com";
36.
37.Stream myRequestStream = request.GetRequestStream();
38.
39.StreamWriter myStreamWriter = new StreamWriter(myRequestStream, Encoding.GetEncoding("gb2312"));
40.
41.myStreamWriter.Write(postDataStr);
42.
43.myStreamWriter.Close();
44.
45.
46.
47.HttpWebResponse response = (HttpWebResponse)request.GetResponse();
48.
49.
50.
51.response.Cookies = cookie.GetCookies(response.ResponseUri);
52.
53.Stream myResponseStream = response.GetResponseStream();
54.
55.StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.GetEncoding("utf-8"));
56.
57.string retString = myStreamReader.ReadToEnd();
58.
59.myStreamReader.Close();
60.
61.myResponseStream.Close();