string(267) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E9%9B%86%E7%BA%BF%E5%99%A8%E7%9A%84%E5%B7%A5%E4%BD%9C%E5%8E%9F%E7%90%86%E6%98%AF%E4%BB%80%E4%B9%88 => Failed to connect to 101.89.117.144 port 38017: Connection refused"
集线器的工作原理是什么
