sudo cp /etc/apt/sources.list /etc/apt/sources.list.old

sudo vim /etc/apt/source.list

sudo gedit /etc/apt/source.list

sudo atom /etc/apt/source.list

deb-src http://mirror.neu.edu.cn/ubuntu/ xenial main restricted #Added by software-properties
deb http://mirror.neu.edu.cn/ubuntu/ xenial main restricted
deb-src http://mirror.neu.edu.cn/ubuntu/ xenial restricted multiverse universe #Added by software-properties
deb http://mirror.neu.edu.cn/ubuntu/ xenial-updates main restricted
deb-src http://mirror.neu.edu.cn/ubuntu/ xenial-updates main restricted multiverse universe #Added by software-properties
deb http://mirror.neu.edu.cn/ubuntu/ xenial universe
deb http://mirror.neu.edu.cn/ubuntu/ xenial-updates universe
deb http://mirror.neu.edu.cn/ubuntu/ xenial multiverse
deb http://mirror.neu.edu.cn/ubuntu/ xenial-updates multiverse
deb http://mirror.neu.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirror.neu.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse #Added by software-properties
deb http://archive.canonical.com/ubuntu xenial partner
deb-src http://archive.canonical.com/ubuntu xenial partner
deb http://mirror.neu.edu.cn/ubuntu/ xenial-security main restricted
deb-src http://mirror.neu.edu.cn/ubuntu/ xenial-security main restricted multiverse universe #Added by software-properties
deb http://mirror.neu.edu.cn/ubuntu/ xenial-security universe
deb http://mirror.neu.edu.cn/ubuntu/ xenial-security multiverse

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

# deb cdrom:[Ubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1)]/ xenial main restricted
deb-src http://archive.ubuntu.com/ubuntu xenial main restricted #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates universe
deb http://mirrors.aliyun.com/ubuntu/ xenial multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse #Added by software-properties
deb http://archive.canonical.com/ubuntu xenial partner
deb-src http://archive.canonical.com/ubuntu xenial partner
deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial-security universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-security multiverse

sudo apt-get update