python writerow乱码怎么解决

import csv

def test_writerow():

    path = "D:/liqian/aa.csv"

    path1 = "D:/liqian/bb.csv"

    with open(path,'rb') as f,open(path1,'ab+') as w:

        for line in f.readlines():  #注意这里的line是字符串，这样直接写会乱码

            print type(line)

            csvw = csv.writer(w)

            csvw.writerow(line)

def test_readrow():

    path = "D:/liqian/aa.csv"

    path1 = "D:/liqian/cc.csv"

    with open(path,'rb') as f,open(path1,'ab+') as w:

        csvr = csv.reader(f)    #利用csv包自带的reader函数，

        csvw = csv.writer(w)   

        for line in csvr:        #这样每一行就是一个列表，可以直接写到新的csv文件

            csvw.writerow(line)

def test_makerow():

    path = "D:/liqian/aa.csv"

    path1 = "D:/liqian/dd.csv"

    with open(path,'rb') as f,open(path1,'ab+') as w:

        csvw = csv.writer(w)

        for line in f.readlines():

            line_list = line.split(",")  

#原文件是csv格式的，所以line是一个包含多个逗号的字符串，这里我用逗号分割，可以形成一个列表

            csvw.writerow(line_list)