python這問題，看了半天看不出來啥問題，運行不出來

#onedayfo = open("air_pollutant.csv", 'r')fw = open("air_pollutant_oneday.csv", 'w')write_str = "City,DATE,PM2.5,PM10,SO2,CO,NO2,O3,LAT,LON\n"fw.write(write_str)line_str = fo.readline()line_str = fo.readline()line_arr = line_str.split(',')while line_str: if line_arr[1] == "2015/12/1": write_str = line_arr[0] + "," + line_arr[1] + "," +line_arr[2] + "," + line_arr[3] +\ "," + line_arr[4] + "," + line_arr[5] + "," + line_arr[6] + "," + line_arr[7] +\ "," + line_arr[8] + "," + line_arr[9] + "," + line_arr[10] fw.write(write_str) line_str = fo.readline() ##### line_arr = line_str.split(',')print("ok")fo.close()fw.close()