using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        int[,] array2D = new int[,] { { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 } };

​

        int[] array1D = new int[] { 10, 20, 30 };

​

        array1D.Select((x, i) => array2D[1, i] = x).ToArray();

        // print to check the array

        for (int j = 0; j < array2D.GetLength(0); j++)

        {

            for (int m = 0; m < array2D.GetLength(1); m++)

            {

                Console.Write(array2D[j, m]);

            }

            Console.WriteLine();

        }

    }

}