（1）编辑源文件，vim /etc/apt/sources.list
中科大镜像源
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-security main restricted universe multiverse
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu/ xenial-security main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
阿里云镜像源
deb http://mirrors.cloud.aliyuncs.com/ubuntu/ trusty main restricted universe multiverse
deb http://mirrors.cloud.aliyuncs.com/ubuntu/ trusty-security main restricted universe multiverse
deb http://mirrors.cloud.aliyuncs.com/ubuntu/ trusty-updates main restricted universe multiverse
deb http://mirrors.cloud.aliyuncs.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb http://mirrors.cloud.aliyuncs.com/ubuntu/ trusty-backports main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse
网易源
deb http://mirrors.163.com/ubuntu/ zesty main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ zesty-security main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ zesty-updates main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ zesty-proposed main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ zesty-backports main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ zesty main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ zesty-security main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ zesty-updates main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ zesty-proposed main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ zesty-backports main restricted universe multiverse