string(256) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E8%AE%BA%E6%96%87%E5%A6%82%E4%BD%95%E6%A0%87%E6%B3%A8%E5%BC%95%E7%94%A8%E9%83%A8%E5%88%86 => Failed to connect to 14.18.117.71 port 38133: Connection refused"
论文如何标注引用部分
