string(247) "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%E6%80%8E%E4%B9%88%E6%A0%87%E5%BC%95%E7%94%A8%E8%A7%92%E6%A0%87 => Failed to connect to 14.18.117.71 port 38220: Connection refused"
论文怎么标引用角标
