ubuntu14.04中一安装软件就出问题，其实是源有问题，源就是软件的来源，只要合适的源就行了，目前有：
根据需要就修改哈！
如果你想速度快点儿，用中科大ubuntu14.04源
deb http://mirrors.ustc.edu.cn/ubuntu/ trusty main restricted universe multiverse
deb http://mirrors.ustc.edu.cn/ubuntu/ trusty-security main restricted universe multiverse
deb http://mirrors.ustc.edu.cn/ubuntu/ trusty-updates main restricted universe multiverse
deb http://mirrors.ustc.edu.cn/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu/ trusty main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu/ trusty-security main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu/ trusty-updates main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu/ trusty-backports main restricted universe multiverse
如果要升级系统，或修复系统，用ubuntu原始源「恢复系统用」
deb cdrom:[Ubuntu 14.04 LTS Trusty Tahr - Release i386 (20140417)]/ trusty main restricted
See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
newer versions of the distribution.
deb http://archive.ubuntu.com/ubuntu trusty main restricted
deb-src http://archive.ubuntu.com/ubuntu trusty main restricted universe multiverse #Added by software-properties
Major bug fix updates produced after the final release of the
distribution.
N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
team. Also, please note that software in universe WILL NOT receive any
review or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu trusty universe
N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
team, and may not be under a free licence. Please satisfy yourself as to
your rights to use the software. Also, please note that software in
multiverse WILL NOT receive any review or updates from the Ubuntu
security team.
deb http://archive.ubuntu.com/ubuntu trusty multiverse
N.B. software from this repository may not have been tested as
extensively as that contained in the main release, although it includes
newer versions of some applications which may provide useful features.
Also, please note that software in backports WILL NOT receive any review
or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu trusty-security main restricted
deb-src http://archive.ubuntu.com/ubuntu trusty-security main restricted universe multiverse #Added by software-properties
deb http://archive.ubuntu.com/ubuntu trusty-security universe
deb http://archive.ubuntu.com/ubuntu trusty-security multiverse
Uncomment the following two lines to add software from Canonical’s
‘partner’ repository.
This software is not part of Ubuntu, but is offered by Canonical and the
respective vendors as a service to Ubuntu users.
deb http://archive.canonical.com/ubuntu trusty partner
deb-src http://archive.canonical.com/ubuntu trusty partner
This software is not part of Ubuntu, but is offered by third-party
developers who want to ship their latest software.
deb http://extras.ubuntu.com/ubuntu trusty main
deb-src http://extras.ubuntu.com/ubuntu trusty main
deb http://archive.ubuntu.com/ubuntu trusty-backports main universe multiverse restricted
deb-src http://archive.ubuntu.com/ubuntu trusty-backports main universe multiverse restricted #Added by software-properties
deb http://archive.ubuntu.com/ubuntu trusty-updates main universe multiverse restricted
deb-src http://archive.ubuntu.com/ubuntu trusty-updates main universe multiverse restricted #Added by software-properties
如果要安装软件，都知道，在ubuntu14.04中不能安装一些软件，用ubuntu安装软件源「使用的是ubuntu13.10」
deb cdrom:[Ubuntu 14.04 LTS Taucy Tahr - Release i386 (20140417)]/ saucy main restricted
See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
newer versions of the distribution.
deb http://archive.ubuntu.com/ubuntu saucy main restricted
deb-src http://archive.ubuntu.com/ubuntu saucy main restricted universe multiverse #Added by software-properties
Major bug fix updates produced after the final release of the
distribution.
N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
team. Also, please note that software in universe WILL NOT receive any
review or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu saucy universe
N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
team, and may not be under a free licence. Please satisfy yourself as to
your rights to use the software. Also, please note that software in
multiverse WILL NOT receive any review or updates from the Ubuntu
security team.
deb http://archive.ubuntu.com/ubuntu saucy multiverse
N.B. software from this repository may not have been tested as
extensively as that contained in the main release, although it includes
newer versions of some applications which may provide useful features.
Also, please note that software in backports WILL NOT receive any review
or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu saucy-security main restricted
deb-src http://archive.ubuntu.com/ubuntu saucy-security main restricted universe multiverse #Added by software-properties
deb http://archive.ubuntu.com/ubuntu saucy-security universe
deb http://archive.ubuntu.com/ubuntu saucy-security multiverse
Uncomment the following two lines to add software from Canonical’s
‘partner’ repository.
This software is not part of Ubuntu, but is offered by Canonical and the
respective vendors as a service to Ubuntu users.
deb http://archive.canonical.com/ubuntu saucy partner
deb-src http://archive.canonical.com/ubuntu saucy partner
This software is not part of Ubuntu, but is offered by third-party
developers who want to ship their latest software.
deb http://extras.ubuntu.com/ubuntu saucy main
deb-src http://extras.ubuntu.com/ubuntu saucy main
deb http://archive.ubuntu.com/ubuntu saucy-backports main universe multiverse restricted
deb-src http://archive.ubuntu.com/ubuntu saucy-backports main universe multiverse restricted #Added by software-properties
deb http://archive.ubuntu.com/ubuntu saucy-updates main universe multiverse restricted
deb-src http://archive.ubuntu.com/ubuntu saucy-updates main universe multiverse restricted #Added by software-properties