StreamReader sr = File.OpenText("e:\\wu.txt");

            StreamWriter srNew = File.CreateText("e:\\wuNew.txt");

            DateTime testTime = new DateTime(2011, 9, 21, 00, 0, 1);

            int i = 0;

            while (!sr.EndOfStream)
            {

                string sLine = sr.ReadLine();

                i++;

                if (i % 60==0)
                {
                    testTime = testTime.AddSeconds(1);
                }

                string newLine = testTime.ToString("yyyy-MM-dd HH:mm:ss") + "  " + sLine;

                srNew.WriteLine(newLine);
            }

            srNew.Close();
            sr.Close();