美国大学的ubuntu源，速度较快
最近一些软件更新源经常出问题，收藏几个避免无源可用。
deb http://mirror.cs.umn.edu/ubuntu/ hardy main restricted universe multiverse deb http://mirror.cs.umn.edu/ubuntu/ hardy-security main restricted universe multiverse deb http://mirror.cs.umn.edu/ubuntu/ hardy-updates main restricted universe multiverse deb http://mirror.cs.umn.edu/ubuntu/ hardy-proposed main restricted universe multiverse deb http://mirror.cs.umn.edu/ubuntu/ hardy-backports main restricted universe multiverse deb-src http://mirror.cs.umn.edu/ubuntu/ hardy main restricted universe multiverse deb-src http://mirror.cs.umn.edu/ubuntu/ hardy-security main restricted universe multiverse deb-src http://mirror.cs.umn.edu/ubuntu/ hardy-updates main restricted universe multiverse deb-src http://mirror.cs.umn.edu/ubuntu/ hardy-proposed main restricted universe multiverse deb-src http://mirror.cs.umn.edu/ubuntu/ hardy-backports main restricted universe multiverse
这里https://launchpad.net/ubuntu/+archivemirrors可以找到一些通过官方认证的源。