这不仅发生在 gettext 上。有很多包我无法安装。它给了我这个错误：
sudo apt install gettext
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Package gettext is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'gettext' has no installation candidate
但是，这个软件包显然适用于我的发行版 Ubuntu 22.04。我已经运行过了sudo apt update，但问题并没有解决。
此外，我的/etc/apt/sources.list看起来很好。
cat /etc/apt/sources.list
# deb cdrom:[Ubuntu 22.04.3 LTS _Jammy Jellyfish_ - Release amd64 (20230807.2)]/ jammy main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://us.archive.ubuntu.com/ubuntu/ jammy restricted
# deb-src http://us.archive.ubuntu.com/ubuntu/ jammy main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://us.archive.ubuntu.com/ubuntu/ jammy-updates restricted
# deb-src http://us.archive.ubuntu.com/ubuntu/ jammy-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://us.archive.ubuntu.com/ubuntu/ jammy universe
# deb-src http://us.archive.ubuntu.com/ubuntu/ jammy universe
deb http://us.archive.ubuntu.com/ubuntu/ jammy-updates universe
# deb-src http://us.archive.ubuntu.com/ubuntu/ jammy-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://us.archive.ubuntu.com/ubuntu/ jammy multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ jammy multiverse
deb http://us.archive.ubuntu.com/ubuntu/ jammy-updates multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ jammy-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://us.archive.ubuntu.com/ubuntu/ jammy-backports restricted universe multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ jammy-backports main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu jammy-security restricted
# deb-src http://security.ubuntu.com/ubuntu jammy-security main restricted
deb http://security.ubuntu.com/ubuntu jammy-security universe
# deb-src http://security.ubuntu.com/ubuntu jammy-security universe
deb http://security.ubuntu.com/ubuntu jammy-security multiverse
# deb-src http://security.ubuntu.com/ubuntu jammy-security multiverse
# This system was installed using small removable media
# (e.g. netinst, live or single CD). The matching "deb cdrom"
# entries were disabled at the end of the installation process.
# For information about how to configure apt package sources,
# see the sources.list(5) manual.
我的系统：
uname -a
Linux queenie 6.5.0-21-generic #21~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Fri Feb 9 13:32:52 UTC 2 x86_64 x86_64 x86_64 GNU/Linux