报必须声明标量变量 "@Number"错误，各位大侠帮忙看一下
using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = "Insert into T_number(number,promary,city,name) values(@Number,@Promary,@City,@Name)";
                    foreach (string file in files)
                    {
                        string[] lines = File.ReadAllLines(file, Encoding.Default);
                        foreach (string line in lines)
                        {
                            string[] strs = line.Split(' ');
                            string Number=strs[0];
                            string Promary=strs[1];
                            string City=strs[2];
                            string Name = strs[3];

                            cmd.Parameters.Clear();
                            cmd.Parameters.Add(new SqlParameter("nubmer", Number));
                            cmd.Parameters.Add(new SqlParameter("promary", Promary));
                            cmd.Parameters.Add(new SqlParameter("city", City));
                            cmd.Parameters.Add(new SqlParameter("name", Name));
                            cmd.ExecuteNonQuery();