deb http://cn.archive.ubuntu.com/ubuntu/ trusty multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty multiverse
deb http://cn.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
deb http://cn.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe
deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe
deb http://security.ubuntu.com/ubuntu/ trusty-security main restricted
deb-src http://security.ubuntu.com/ubuntu/ trusty-security main restricted
deb http://security.ubuntu.com/ubuntu/ trusty-security universe
deb-src http://security.ubuntu.com/ubuntu/ trusty-security universe
deb http://security.ubuntu.com/ubuntu/ trusty-security multiverse
deb-src http://security.ubuntu.com/ubuntu/ trusty-security multiverse
原文：http://www.cnblogs.com/nianzhen/p/5041064.html