安装完Ubuntu 16.04后，要更换为国内的软件源：
sudo gedit /etc/apt/sources.list #用文本编辑器打开源列表
在文件开头添加下面的阿里云的软件源：
deb http://mirrors.aliyun.com/ubuntu/ quantal main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ quantal-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ quantal-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ quantal-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ quantal-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ quantal main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ quantal-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ quantal-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ quantal-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ quantal-backports main restricted universe multiverse
更新软件源： sudo apt-get update
其他软件源也可以，阿里云的软件源是Ubuntu官方推荐的国内软件源。,清华的软件源也可以。