sudo add-apt-repository ppa:kubuntu-ppa/backports
sudo apt update
sudo apt install kubuntu-desktop kde-plasma-desktop

切换 DM

sudo dpkg-reconfigure lightdm

lightdm 和 sddm 的区别：
https://wiki.archlinux.org/index.php/Display_manager_(%E7%AE%80%E4%BD%93%E4%B8%AD%E6%96%87)

安装教程：
https://techviewleo.com/how-to-install-kde-plasma-desktop-on-linux-mint/