从chrome中copy出来的XPath,在lxml.etree.HTML中无法生效是怎么回事?

描述问题

想对html内容使用XPath选择器
步骤是:

1. 种chrome右键得到XPath选择器

2. 在lxml中使用

但是:

1. 按理来说能选到, 但是返回的是空列表

上下文环境

python 2.7.11+ (default, Apr 17 2016, 14:00:29) 
[GCC 5.3.1 20160413] on linux2



 pip show lxml
---
Metadata-Version: 1.1
Name: lxml
Version: 3.5.0
Summary: Powerful and Pythonic XML processing library combining libxml2/libxslt with the ElementTree API.
Home-page: http://lxml.de/
Author: lxml dev team
Author-email: lxml-dev@lxml.de
License: UNKNOWN
Location: /usr/lib/python2.7/dist-packages
Requires: 
Classifiers:
  Development Status :: 5 - Production/Stable
  Intended Audience :: Developers
  Intended Audience :: Information Technology
  License :: OSI Approved :: BSD License
  Programming Language :: Cython
  Programming Language :: Python :: 2
  Programming Language :: Python :: 2.6
  Programming Language :: Python :: 2.7
  Programming Language :: Python :: 3
  Programming Language :: Python :: 3.2
  Programming Language :: Python :: 3.3
  Programming Language :: Python :: 3.4
  Programming Language :: Python :: 3.5
  Programming Language :: C
  Operating System :: OS Independent
  Topic :: Text Processing :: Markup :: HTML
  Topic :: Text Processing :: Markup :: XML
  Topic :: Software Development :: Libraries :: Python Modules

重现

1. 拷贝代码, 运行

2. 注意代码中的url, 可以在chrome中做实验, 确实这个选择器, Firefox中XPath选择有所不同

相关代码

from __future__ import absolute_import, unicode_literals

from lxml.etree import HTML
import requests


def get_text(url):
    return requests.get(url).text

page = HTML(get_text('http://v2ex.com/?tab=hot'))
print page.xpath('//*[@id="Main"]/div[2]/div[10]/table/tbody/tr/td[3]/span[1]/a')  #这里没有选到内容, 按理来说要选到

报错信息

相关截图

已经尝试哪些方法仍然没有解决(附上相关链接)

1. 猜测lxml的规则有所不同? (但是使用css选择器, 则没有问题)

问题简化

---

答案也许是这个https://www.zhihu.com/question/41221020

真是坑啊, 如果不多搜索下, 又得浪费多少时间...

lxml的官网排版就是一坨shi