string(238) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E7%9F%AD%E8%B7%AF%E5%92%8C%E6%96%AD%E8%B7%AF%E7%9A%84%E5%AE%9A%E4%B9%89 => Failed to connect to 61.171.74.35 port 38027: Connection refused"
短路和断路的定义
