python这问题，看了半天看不出来啥问题，运行不出来

#oneday
fo = 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()

你是要实现什么功能？可以考虑直接用csv模块操作csv文件，都封装好了。

mark