string(247) "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%8A%9F%E8%83%BD%E6%98%AF%E4%BB%80%E4%B9%88 => Failed to connect to 61.171.74.35 port 38041: Connection refused"
集线器的功能是什么
