string(238) "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%91%98%E8%A6%81%E6%A0%BC%E5%BC%8F%E6%A8%A1%E6%9D%BF => Failed to connect to 61.171.74.35 port 38027: Connection refused"
论文摘要格式模板
