string(230) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E5%85%B3%E9%94%AE%E8%AF%8D%E5%AF%86%E5%BA%A6%E8%B6%8A%E9%AB%98%E8%B6%8A%E5%A5%BD => Received HTTP code 403 from proxy after CONNECT"
关键词密度越高越好
