我用下面的代码把一个网页下载了下来！但是出现一下以"&#"开头的字符，像：
"资料图片：波音737\x3cb\x3e飞机"
请问这些是什么字符，如何还原呢？

下载代码：
public void DownloadHtml(string downUrl, ref string context)
        {
            try
            {
                HttpWebRequest req = (HttpWebRequest)WebRequest.Create(downUrl);
                req.Timeout = 10000;
                using (HttpWebResponse resp = (HttpWebResponse)req.GetResponse())
                using (Stream stream = resp.GetResponseStream())
                using (MemoryStream mem = new MemoryStream())
                {
                    int blockSize = 16384;
                    byte[] blockBuffer = new byte[blockSize];
                    int read = 0;

                    while ((read = stream.Read(blockBuffer, 0, blockSize)) > 0)
                    {
                        mem.Write(blockBuffer, 0, read);
                    }

                    mem.Seek(0, SeekOrigin.Begin);

                    byte[] binaryContent = mem.GetBuffer();

                    Encoding encoding = Encoding.UTF8;
                    context = encoding.GetString(binaryContent);
                }
            }