2. 提示用户输入密码，如果密码是“888888”则提示正确，否则要求再输入一次，如果密码是“888888”则提示正确，否则提示错误。

            Console.WriteLine("请输入密码:");            

          string password = Console.ReadLine();            

          if (password == "888888")            

          { Console.WriteLine("密码正确！"); }            

          else            {                 Console.WriteLine("请重新输入密码：");                        

          password = Console.ReadLine();               

           if (password == "888888")               

         { Console.WriteLine("密码正确！"); }               

        else { Console.WriteLine("密码错误！"); }             }

                Console.ReadKey();