更换服务器的源
Ubuntu 的源和安装系统时选择的语言有关系，如果是英文，源是美国那边的，有时候更新很慢。可以通过更换国内的源解决。
//先备份原来的文件
sudo cp /etc/apt/sources.list /etc/apt/source.list.old
sudo vim /etc/apt/sources.list
//选择下面的一个源复制进去
//保存退出
sudo apt-get update
东北大学源：
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
清华大学源：
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
阿里云源：
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
