Python HTTP错误416：请求的范围不满足

Question

import urllib2

url = 'http://www....'
opener = urllib2.build_opener()
opener.addheaders.append(('User-Agent' , 'Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)')) 
c = opener.open(url)

使用此代码，我收到此错误：

HTTP Error 416: Requested Range Not Satisfiable

我该如何解决？