修改sources.list文件
vim /etc/apt/sources.list
输入如下内容并保存退出：
#阿里云
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
deb-src http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse
#Ubuntu 官方源
#deb http://archive.ubuntu.com/ubuntu/ gutsy main restricted universe multiverse
#deb http://archive.ubuntu.com/ubuntu/ gutsy-security main restricted universe multiverse
#deb http://archive.ubuntu.com/ubuntu/ gutsy-updates main restricted universe multiverse
#deb http://archive.ubuntu.com/ubuntu/ gutsy-proposed main restricted universe multiverse
#deb http://archive.ubuntu.com/ubuntu/ gutsy-backports main restricted universe multiverse
#deb-src http://archive.ubuntu.com/ubuntu/ gutsy main restricted universe multiverse
#deb-src http://archive.ubuntu.com/ubuntu/ gutsy-security main restricted universe multiverse
#deb-src http://archive.ubuntu.com/ubuntu/ gutsy-updates main restricted universe multiverse
#deb-src http://archive.ubuntu.com/ubuntu/ gutsy-proposed main restricted universe multiverse
#deb-src http://archive.ubuntu.com/ubuntu/ gutsy-backports main restricted universe multiverse
更新apt软件源：
apt-get update