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%E6%AF%94%E4%BE%8B%E5%85%B3%E7%B3%BB => Failed to connect to 218.78.59.96 port 38043: Connection refused"
带宽和速率的比例关系
