import os
from urllib.request import urlretrieve
from urllib.request import Request, urlopen
import bs4
url='http://cjc.ict.ac.cn/qwjs/No2020-01.htm'
header = {
'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.105 Safari/537.36'}
ret