修改/etc/app/sources.list
deb http://cn.archive.ubuntu.com/ubuntu/ trusty main restricted universe multiverse
deb http://cn.archive.ubuntu.com/ubuntu/ trusty-security main restricted universe multiverse
deb http://cn.archive.ubuntu.com/ubuntu/ trusty-updates main restricted universe multiverse
deb http://cn.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse
##测试版源
deb http://cn.archive.ubuntu.com/ubuntu/ trusty-proposed main restricted universe multiverse
# 源码
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty main restricted universe multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-security main restricted universe multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-updates main restricted universe multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse
##测试版源
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-proposed main restricted universe multiverse
# Canonical 合作伙伴和附加
deb http://archive.canonical.com/ubuntu/ trusty partner
deb http://extras.ubuntu.com/ubuntu/ trusty main