WebClient下载压缩网页时出现的全是乱码，可通过扩展来解决这个问题。

public class MyWebClient : WebClient    {        protected override WebRequest GetWebRequest(Uri url)        {            HttpWebRequest request = base.GetWebRequest(url) as HttpWebRequest;            request.AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip;            return request;        }    }