该页面似乎拒绝GET了未标识的请求User-Agent。我使用浏览器（Chrome）访问了该页面，并复制User- Agent了GET请求的标题（在开发人员工具的“网络”标签中查看）：
import requests
url = 'http://worldagnetwork.com/'
headers = {'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.102 Safari/537.36'}
result = requests.get(url, headers=headers)
print(result.content.decode())
# <!doctype html>
# <!--[if lt IE 7 ]><html class="no-js ie ie6" lang="en"> <![endif]-->
# <!--[if IE 7 ]><html class="no-js ie ie7" lang="en"> <![endif]-->
# <!--[if IE 8 ]><html class="no-js ie ie8" lang="en"> <![endif]-->
# <!--[if (gte IE 9)|!(IE)]><!--><html class="no-js" lang="en"> <!--<![endif]-->
# ...
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