我在尝试安装 opencv 和 python 包时执行 sudo apt-get update 时遇到以下问题：
root@ubuntu:~# apt-get update
Ign:1 cdrom://Ubuntu 16.04.2 LTS _Xenial Xerus_ - Release amd64 (20170215.2) xenial InRelease
Hit:2 cdrom://Ubuntu 16.04.2 LTS _Xenial Xerus_ - Release amd64 (20170215.2) xenial Release Ign:4 http://dl.google.com/linux/chrome/deb stable InRelease Hit:5 http://dl.google.com/linux/chrome/deb stable Release Get:6 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB] Hit:8 http://archive.ubuntu.com/ubuntu xenial InRelease Get:9 http://archive.ubuntu.com/ubuntu xenial-updates InRelease [102 kB] Get:10 http://security.ubuntu.com/ubuntu xenial-security/main amd64 DEP-11 Metadata [60.2 kB] Ign:11 http://www.openprinting.org/download/printdriver/debian lsb3.2 InRelease Get:12 http://security.ubuntu.com/ubuntu xenial-security/main DEP-11 64x64 Icons [57.6 kB] …