使用python仅从csv文件中获取所需的行

Question

如何使用python从csv文件中获取每3行？你知道吗

import csv

with open ('data.csv','r') as infile:
    contents = csv.reader(infile, delimiter =' ')
then???

csv文件如下所示：

aaaaaaaaaaaaaaaa
bbbbbbbbbbbbbbbb
only recquired line
cccccccccccccccccccccccccc
ddddddddddddddddddddddddd
only recquired line

结果应该如下所示：

only recquired line
only recquired line

Answer 1

with open('test.csv') as hf:
    print [line for line in list(hf)[2::3]]