ArrayList URLs = new ArrayList();
 ArrayList Duplicated = new ArrayList();
 byte[] data = wc.DownloadData("https://www.bing.com/search?q=" + keyword);
                MatchCollection M = Regex.Matches(Encoding.UTF8.GetString(data, 0, data.Length), "[a-z]+[:][/][/][a-z]+[.][a-zA-Z0-9]+[.][a-z]+");
                foreach (Match m in M)
                    Duplicated.Add(m.Value);
                foreach (string line in Duplicated)
                    URLs.Add(line);
                for (int i = 0; i < Duplicated.Count; i++)
                {
                    if (URLs.Contains(Duplicated[i]))
                        URLs.Remove(Duplicated[i]);
                }
                foreach (string line in URLs)
                    richTextBox1.AppendText(line + "rn");