string(244) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=usb3.0%E7%9A%84%E4%BC%A0%E8%BE%93%E9%80%9F%E5%BA%A6%E4%B8%BA%E5%A4%9A%E5%B0%91 => Failed to connect to 14.18.117.71 port 38133: Connection refused"
usb3.0的传输速度为多少
