string(247) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E5%87%80%E5%88%A9%E6%B6%A6%E7%9A%84%E5%85%AC%E5%BC%8F%E6%98%AF%E5%A4%9A%E5%B0%91 => Failed to connect to 61.171.74.35 port 38041: Connection refused"
净利润的公式是多少
