我在 Nexus 5 手机上安装了 Ubuntu Touch，但无法使用 apt-get 安装任何程序。你能帮助我吗？
phablet@ubuntu-phablet:/etc/apt$ uname -a
Linux ubuntu-phablet 3.4.0-cyanogenmod-g2669fa0 #1 SMP PREEMPT Fri Aug 24 02:24:01 CEST 2018 armv7l armv7l armv7l GNU/Linux
phablet@ubuntu-phablet:/etc/apt$ cat /etc/apt/sources.list
## EOL upgrade sources.list
# Required
deb http://old-releases.ubuntu.com/ubuntu/ xenial main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ xenial-updates main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ xenial-security main restricted universe multiverse
phablet@ubuntu-phablet:/etc/apt$ sudo apt clean && sudo apt update
Hit:1 http://ppa.launchpad.net/mc3man/xerus-media/ubuntu xenial InRelease
Ign:2 http://old-releases.ubuntu.com/ubuntu xenial InRelease
Ign:3 http://repo.ubports.com xenial InRelease
Hit:4 http://ppa.launchpad.net/phablet-team/tools/ubuntu xenial InRelease
Ign:5 http://old-releases.ubuntu.com/ubuntu xenial-updates InRelease
Hit:6 http://repo.ubports.com xenial Release
Ign:7 http://old-releases.ubuntu.com/ubuntu xenial-security InRelease
Err:8 http://old-releases.ubuntu.com/ubuntu xenial Release
404 Not Found [IP: 91.189.88.41 80]
Err:9 http://old-releases.ubuntu.com/ubuntu xenial-updates Release
404 Not Found [IP: 91.189.88.41 80]
Err:10 http://old-releases.ubuntu.com/ubuntu xenial-security Release
404 Not Found [IP: 91.189.88.41 80]
Reading package lists... Done
E: The repository 'http://old-releases.ubuntu.com/ubuntu xenial Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://old-releases.ubuntu.com/ubuntu xenial-updates Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://old-releases.ubuntu.com/ubuntu xenial-security Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.