http://wiki.ubuntu.org.cn/Template:12.04source
deb http://cn.archive.ubuntu.com/ubuntu/ precise main restricted universe multiverse deb http://cn.archive.ubuntu.com/ubuntu/ precise-security main restricted universe multiverse deb http://cn.archive.ubuntu.com/ubuntu/ precise-updates main restricted universe multiverse deb http://cn.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse ##测试版源 deb http://cn.archive.ubuntu.com/ubuntu/ precise-proposed main restricted universe multiverse
# 源码 deb-src http://cn.archive.ubuntu.com/ubuntu/ precise main restricted universe multiverse deb-src http://cn.archive.ubuntu.com/ubuntu/ precise-security main restricted universe multiverse deb-src http://cn.archive.ubuntu.com/ubuntu/ precise-updates main restricted universe multiverse deb-src http://cn.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse ##测试版源 deb-src http://cn.archive.ubuntu.com/ubuntu/ precise-proposed main restricted universe multiverse
# Canonical 合作伙伴和附加 deb http://archive.canonical.com/ubuntu/ precise partner deb http://extras.ubuntu.com/ubuntu/ precise main
原文：http://www.cnblogs.com/felixjia/p/5448464.html