string(243) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=roi%E6%8A%95%E8%B5%84%E5%9B%9E%E6%8A%A5%E7%8E%87%E6%80%8E%E4%B9%88%E7%AE%97 => Failed to connect to 101.89.117.144 port 38056: Connection refused"
roi投资回报率怎么算
