国内源速度比较快

 deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse
  deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse
  deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse
  deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
  ##测试版源
  deb http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse
  # 源码
  deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse
  deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse
  deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse
  deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
  ##测试版源
  deb-src http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse
  # Canonical 合作伙伴和附加
  deb http://archive.canonical.com/ubuntu/ xenial partner
  deb http://extras.ubuntu.com/ubuntu/ xenial main

更新下源
sudo apt-get update

其他命令

sudo apt-get update  更新源
sudo apt-get install package 安装包
sudo apt-get remove package 删除包
sudo apt-cache search package 搜索软件包
sudo apt-cache show package  获取包的相关信息，如说明、大小、版本等
sudo apt-get install package --reinstall  重新安装包
sudo apt-get -f install  修复安装
sudo apt-get remove package --purge 删除包，包括配置文件等
sudo apt-get build-dep package 安装相关的编译环境
sudo apt-get upgrade 更新已安装的包
sudo apt-get dist-upgrade 升级系统
sudo apt-cache depends package 了解使用该包依赖那些包
sudo apt-cache rdepends package 查看该包被哪些包依赖
sudo apt-get source package  下载该包的源代码
sudo apt-get clean && sudo apt-get autoclean 清理无用的包
sudo apt-get check 检查是否有损坏的依赖