deb http://mirrors.163.com/ubuntu/ xenial main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ xenial-security main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ xenial-updates main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ xenial-proposed main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ xenial-backports main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ xenial main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ xenial-security main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ xenial-updates main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ xenial-proposed main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ xenial-backports main restricted universe multiverse