string(258) "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%E4%B8%89%E4%B8%AA%E8%AE%A1%E7%AE%97%E5%85%AC%E5%BC%8F => Failed to connect to 101.89.159.206 port 38087: Connection refused"
净利润的三个计算公式
