问为什么这个Wikipedia mediawiki api请求不将类别返回到所有链接？

EN

# -*- coding: utf-8 -*-
import urllib.request
import urllib.parse
import json

def link_request(more_parameters={"continue": ""}):
   parameters = {"format": "json",
                 "action": "query",
                 "generator": "links",
                 "gpllimit": "max",
                 "gplnamespace": "0",
                 "prop": "categories",
                 "cllimit": "max",
                 "titles": urllib.parse.quote(start_page.encode("utf8"))}
   parameters.update(more_parameters)

   queryString = "&".join("%s=%s" % (k, v) for k, v in parameters.items())

   # This ensures that redirects are followed automatically, documented here:
   # http://www.mediawiki.org/wiki/API:Query#Resolving_redirects
   queryString = queryString+"&redirects"

   url = "http://%s.wikipedia.org/w/api.php?%s" % (wikipedia_language, queryString)
   print(url)

   #get json data from wikimedia API and make a dictionary out of it:
   request = urllib.request.urlopen(url)
   encoding = request.headers.get_content_charset()
   jsonData = request.read().decode(encoding)
   data = json.loads(jsonData)

   return data

def get_link_data():
   data=link_request()

   query_result=data['query']['pages']

   while 'continue' in data.keys():
      continue_dict=dict()
      for key in list(data['continue'].keys()):
         if key == 'continue':
            continue_dict.update({key: data['continue'][key]})
         else:
            val= "|".join([urllib.parse.quote(e) for e in data['continue'][key].split('|')])
            continue_dict.update({key: val})
      data=link_request(continue_dict)
      query_result.update(data['query']['pages'])

   print(json.dumps(query_result, indent=4))

start_page="Albert Einstein"
wikipedia_language="en"
get_link_data()