string(230) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E7%9B%AE%E6%A0%87%E7%BE%A4%E4%BD%93%E5%88%92%E5%88%86%E7%9A%84%E4%BD%9C%E7%94%A8 => Received HTTP code 403 from proxy after CONNECT"
目标群体划分的作用
