返回以下错误：
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
build-essential : Depends: libc6-dev but it is not going to be installed or
libc-dev
Depends: g++ (>= 4:9.2) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
我已尝试过sudo apt-get update，sudo apt install cmake但错误是一样的。
输出apt-cache policy build-essential libc6-dev libc6 libc-dev g++ cmake
build-essential:
Installed: (none)
Candidate: 12.8ubuntu1
Version table:
12.8ubuntu1 500
500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages
libc6-dev:
Installed: (none)
Candidate: 2.31-0ubuntu9
Version table:
2.31-0ubuntu9 500
500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages
libc6:
Installed: 2.31-0ubuntu9.3
Candidate: 2.31-0ubuntu9.3
Version table:
*** 2.31-0ubuntu9.3 100
100 /var/lib/dpkg/status
2.31-0ubuntu9 500
500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages
libc-dev:
Installed: (none)
Candidate: (none)
Version table:
g++:
Installed: (none)
Candidate: 4:9.3.0-1ubuntu2
Version table:
4:9.3.0-1ubuntu2 500
500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages
cmake:
Installed: 3.16.3-1ubuntu1
Candidate: 3.16.3-1ubuntu1
Version table:
*** 3.16.3-1ubuntu1 500
500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages
100 /var/lib/dpkg/status
输出sudo apt update
Hit:1 http://archive.ubuntu.com/ubuntu focal InRelease
Hit:2 http://ppa.launchpad.net/jonmagon/kdiskmark/ubuntu focal InRelease
Hit:3 http://dl.google.com/linux/chrome/deb stable InRelease
Ign:4 http://repo.vivaldi.com/stable/deb stable InRelease
Hit:5 http://packages.microsoft.com/repos/code stable InRelease
Hit:6 http://apt.insync.io/ubuntu focal InRelease
Hit:7 http://repo.vivaldi.com/stable/deb stable Release
Hit:8 https://download.docker.com/linux/ubuntu focal InRelease
Hit:9 https://download.sublimetext.com apt/stable/ InRelease
** grep ^deb -r /etc/apt/ --include=*.list**
said@~/Projects/Rust/hello_world$ grep ^deb -r /etc/apt/ --include=*.list
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu focal main universe restricted
/etc/apt/sources.list:deb-src http://archive.ubuntu.com/ubuntu focal main universe restricted #Added by software-properties
/etc/apt/sources.list.d/insync.list:deb http://apt.insync.io/ubuntu/ focal non-free contrib
/etc/apt/sources.list.d/vivaldi.list:deb http://repo.vivaldi.com/stable/deb/ stable main
/etc/apt/sources.list.d/google-chrome.list:deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main
/etc/apt/sources.list.d/jonmagon-ubuntu-kdiskmark-focal.list:deb http://ppa.launchpad.net/jonmagon/kdiskmark/ubuntu/ focal main
/etc/apt/sources.list.d/vscode.list:deb [arch=amd64,arm64,armhf] http://packages.microsoft.com/repos/code/ stable main
/etc/apt/sources.list.d/docker.list:deb [arch=amd64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu/ focal stable
/etc/apt/sources.list.d/sublime-text.list:deb https://download.sublimetext.com/ apt/stable/
更新：
我不得不重新安装 Kubuntu 20.04。这是一次肮脏的安装，其中格式化/和/boot挂载点已经发生但/home保持原样，然后创建与上次安装同名的用户以保持家庭设置完好无损。
我认为这是基于 Debian 的发行版的一个主要缺点。我认为 Fedora或 OpenSuseapt找不到它。但是，我认为在使用之前应该先使用，甚至从 *.deb 文件安装也应该如此。dnfyumapt installapt update