string(248) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E6%8A%95%E5%85%A5%E4%BA%A7%E5%87%BA%E6%AF%94%E5%85%AC%E5%BC%8F%E8%AE%A1%E7%AE%97 => Failed to connect to 101.91.112.32 port 38221: Connection refused"
投入产出比公式计算
