---

int[,] mas = {
    { 1, 2, 3 },
    { 4, 5, 6 },
    { 7, 8, 9 },
    { 10, 11, 12 }
};

int rows = mas.GetLength(0);
int columns = mas.GetLength(1);

for (int i = 0; i < rows; i++)
{
    for (int j = 0; j < columns; j++)
    {
        Console.Write($"{mas[i, j]}\t");
    }
    Console.WriteLine();
}