编辑 /etc/apt/source.list

 

# deb cdrom:[Ubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1)]/ xenial main restricted
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial universe
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates universe
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial multiverse
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates multiverse
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security universe
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security multiverse