using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        Dictionary<string, string> g = new Dictionary<string, string>();

        g.Add("K", "k1");

        g.Add("L", "l1");

        var keys1 = g.Select(x => String.Format("{0}=@{0}", x.Key));

        var result1 = string.Join(",", keys1);

        Console.WriteLine(result1);

        var keys2 = g.Select(x => String.Format("{0}={1}", x.Key, x.Value));

        var result2 = string.Join(",", keys2);

        Console.WriteLine(result2);

    }

}