string(250) "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%92%8CROI%E4%B8%80%E6%A0%B7%E5%90%97 => Failed to connect to 14.18.117.71 port 38220: Connection refused"
投入产出比和ROI一样吗
