求助，ubuntu中勾选了universe源，但apt-get install时很多软件还是找不到。

如题，在Software & Updates菜单里已经勾选了 “社区维护的免费和开元软件(universe)” 选项，在安装软件的时候，还是提示找不到。
而且在ubuntu软件中心也是提示 "universe" 源没有开启。
具体看图。










/etc/apt/sources.list 内容如下：

# deb cdrom:[Ubuntu 13.04 _Raring Ringtail_ - Release i386 (20130424)]/ raring main restricted

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://mirrors.163.com/ubuntu/ raring main restricted
deb-src http://mirrors.163.com/ubuntu/ raring main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://mirrors.163.com/ubuntu/ raring-updates main restricted
deb-src http://mirrors.163.com/ubuntu/ raring-updates main restricted

## 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://mirrors.163.com/ubuntu/ raring universe
deb-src http://mirrors.163.com/ubuntu/ raring universe
deb http://mirrors.163.com/ubuntu/ raring-updates universe
deb-src http://mirrors.163.com/ubuntu/ raring-updates 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://mirrors.163.com/ubuntu/ raring multiverse
deb-src http://mirrors.163.com/ubuntu/ raring multiverse
deb http://mirrors.163.com/ubuntu/ raring-updates multiverse
deb-src http://mirrors.163.com/ubuntu/ raring-updates 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://mirrors.163.com/ubuntu/ raring-backports main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ raring-backports main restricted universe multiverse

deb http://mirrors.163.com/ubuntu/ raring-security main restricted
deb-src http://mirrors.163.com/ubuntu/ raring-security main restricted
deb http://mirrors.163.com/ubuntu/ raring-security universe
deb-src http://mirrors.163.com/ubuntu/ raring-security universe
deb http://mirrors.163.com/ubuntu/ raring-security multiverse
deb-src http://mirrors.163.com/ubuntu/ raring-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 raring partner
# deb-src http://archive.canonical.com/ubuntu raring 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 raring main
deb-src http://extras.ubuntu.com/ubuntu raring main