static void Main(string[] args)

        {

            string name = "asher";

            //方法1

            string str1 = "hello " + name;

            //方法2

            string str2 = string.Format("hello {0}", name);

            //方法3

            string str3 = $"hello {name}";

            Console.WriteLine(str1);

            Console.WriteLine(str2);

            Console.WriteLine(str3);

            Console.ReadKey();

        }