1. 使用 lsb_release -a 查询系统版本信息
重点关注 Codename 字段
2. 使用 root 用户修改 /etc/apt/sources.list
建议先进行备份：cp /etc/apt/sources.list /etc/apt/sources.list.bak
清空 /etc/apt/sources.list 原先的内容，修改为如下内容：
deb http://mirrors.aliyun.com/ubuntu/ yakkety main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ yakkety-backports main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ yakkety-proposed main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ yakkety-security main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ yakkety-updates main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ yakkety main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ yakkety-backports main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ yakkety-proposed main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ yakkety-security main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ yakkety-updates main multiverse restricted universe
注：将其中的 yakkety 修改为你系统的Codename
3. 使用 apt-get install update, apt-get install upgrade 更新软件源
