无法打印字符串，提示索引错误。substring

string poetry = "日照香炉生紫烟，遥看瀑布观前川，飞流直下三千尺，疑是银河落九天。\n";
                 int i=1, j=1,z=0;
                 string [] s = new string[4] ;
                 string char1= "";
                 char1 = "";
                 char1 = "poetry .Substring (1,2)";
                 Console.Write("{1}/n", char1);