string(267) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E4%BA%92%E8%81%94%E7%BD%91%E5%BA%94%E7%94%A8%E6%8A%80%E6%9C%AF%E5%8F%91%E5%B1%95%E7%9A%843%E4%B8%AA%E9%98%B6%E6%AE%B5 => Received HTTP code 403 from proxy after CONNECT"
互联网应用技术发展的3个阶段
