string(256) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E5%B8%A6%E5%AE%BD%E5%92%8C%E9%80%9F%E7%8E%87%E7%9A%84%E5%85%B3%E7%B3%BB%E5%85%AC%E5%BC%8F => Failed to connect to 14.18.117.71 port 38041: Connection refused"
带宽和速率的关系公式
