string(250) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E7%94%B5%E5%95%86roi%E4%B8%80%E8%88%AC%E6%98%AF%E5%A4%9A%E5%B0%91%E6%AD%A3%E5%B8%B8 => Failed to connect to 14.18.117.71 port 38164: Connection refused"
电商roi一般是多少正常
