import?urllib.request,re
req=urllib.request.urlopen('http://www.xianlaiwan.cn/course/list')
buf=req.read().decode('utf-8')
listurl=re.findall(r'src.+.jpg',buf)
list_url=re.sub(r'src="','http:',str(listurl))
i=0
for?url?in?list_url:
????f=open(str(i)+'.jpg','wb')
????req=urllib.request.urlopen(url)
????buf=req.read()
????f.write(buf)
????i=i+1
????f.close

第9行報錯ValueError: unknown url type: '[' ?是什么情況呢