执行命令：
sudo apt install gcc
具体错误
Media change: please insert the disc labeled 'Ubuntu 20.04.4 LTS _Focal Fossa_ - Release amd64 (20220223)' in the drive '/cdrom/' and press [Enter]
解决办法
/etc/apt/sources.list文件，注释掉cdrom一行，例如：
# deb cdrom:[Ubuntu 20.04.4 LTS _Focal Fossa_ - Release amd64 (20220223)]/ focal main restricted
再次执行命令，成功
