string(240) "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%E4%B8%80%E8%88%AC%E6%A0%BC%E5%BC%8F => Failed to connect to 101.89.159.206 port 38100: Connection refused"
论文摘要一般格式
