int[,] arr2 ={ { 1, 2, 3 }, { 4, 5, 6 } };
            Console.Write("数组的行数为：");
            Console.Write(arr2.Rank);
            Console.Write("\n>");
            Console.Write("数组的列数为：");
            Console.Write(arr2.GetUpperBound(arr2.Rank-1)+1);这句不明白是什么意思，书上没有详细的解释。还有下面的循环也不是很明白，getupperbound 和rand都是什么意思。。麻凡您了，谢谢
            Console.Write("\n>");
            for (int i = 0; i < arr2.Rank; i++)
            {
                string s = "";
                for (int j = 0; j < arr2.GetUpperBound(arr2.Rank - 1) + 1; j++)
                {
                    s = s + Convert.ToString(arr2[i, j]) + "";

                }

                Console.Write(s);
                Console.Write("\n>");
            }
            Console.Read();