scrapy运行后一直爬不到任何item怎么处理？

以下是spider的代码

import re
import json


from scrapy.selector import Selector
try:
    from scrapy.spider import Spider
except:
    from scrapy.spider import BaseSpider as Spider
from scrapy.utils.response import get_base_url
from scrapy.utils.url import urljoin_rfc
from scrapy.contrib.spiders import CrawlSpider, Rule
from scrapy.contrib.linkextractors.sgml import SgmlLinkExtractor as sle


from tuniu.items import *
from tuniu.misc.log import *

class TuniuSpider(CrawlSpider):
    name = "tuniu"
    allowed_domains = ["tuniu.com"]
    start_urls = [
        "http://www.tuniu.com/"
    ]
    rules = [
       
        #Rule(sle(allow=(".*?\.tuniu.com/.*?", )), follow=True,callback='parse_item'),          
        Rule(sle(allow=("/guide/d\-(.*?)\-\d{1,6}/.*", )), follow=True,callback='parse_item'),
        Rule(sle(allow=("/.*?/whole-.*?-0/.*", )), follow=True,callback='parse_item'),
    ]

    def parse_item(self, response):
        items = []
        sel = Selector(response)
        base_url = get_base_url(response)
        sites_even = sel.css('content')
        for site in sites_even:
            item = TuniuItem()
            
            item['price'] = site.css('.num span').xpath('text()').extract()[0]
           
            items.append(item)
            #print repr(item).decode("unicode-escape") + '\n'

            info('parsed ' + str(response))
        return items
    
    def _process_request(self, request):
        info('process ' + str(request))
        return request