string(237) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E4%BF%A1%E5%8F%B7%E4%B8%AD%E5%B8%A6%E5%AE%BD%E7%9A%84%E5%AE%9A%E4%B9%89 => Failed to connect to 14.18.46.51 port 38206: Connection refused"
信号中带宽的定义
