string(274) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E5%A6%82%E4%BD%95%E8%AE%A1%E7%AE%97%E6%8E%A8%E5%B9%BF%E8%B4%B9%E7%94%A8%E7%9A%84%E5%85%AC%E5%BC%8F%E6%98%AF => Failed to connect to 61.171.74.35 port 38027: Connection refused"
如何计算推广费用的公式是
