keys = new List<string>();
                    string[] strArr = new string[2]; 
               
 
                    for (int xx = 0; xx < ds.Tables[0].Rows.Count; ++xx)
                    {
                        com = "COM" + dt.Rows[xx][7];
                        send = dt.Rows[xx][3].ToString() + "\r";
                        strArr[0] = com; strArr[1] = send;
                        keys.AddRange(strArr);
                    }
                    label1.Text = keys[0];
                    label2.Text = keys[1];
                    label3.Text = keys[2];
                    label4.Text = keys[3];

class Pair<T>
    {
        public Pair(T first,T second)
        {
            First = first;
            Second = second;
        }
        public T First { get; set; }
        public T Second { get; set; }
    }
    class Program
    {
        static void Main(string[] args)
        {
            List<Pair<int>> mas = new List<Pair<int>>();
            mas.Add(new Pair<int>(5, 7));
            Console.WriteLine(mas[0].First + " " + mas[0].Second);
        }
    }