直接编辑：sudo /etc/apt/sources.list文件
deb http://源地址/ubuntu/ xenial main universe restricted multiversedeb http://源地址/ubuntu/ xenial-updates main universe restricted multiversedeb http://源地址/ubuntu/ xenial-backports main restricted universe multiversedeb http://源地址/ubuntu/ xenial-security main universe restricted multiversedeb http://源地址/ubuntu/ xenial-proposed main universe restricted multiverse改完后运行：sudo apt-get update升级索引
