public static void Main()
int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 };
int[] numbersB = { 1, 3, 5, 7, 8 };
var pairs = numbersA.SelectMany(a => numbersB.Where(b => b>a)
.Select(b => new { a, b }));
foreach(var pair in pairs)
Console.WriteLine(String.Format("a={0},b={1}",pair.a,pair.b));