我在 ubuntu 18.04 上安装了 Mate-Desktop，然后我删除了它，但 Grub 加载程序没有被删除/更改，它仍然以 Mate 徽标启动，我需要默认的 Ubuntu 加载程序，如何将其恢复
营业额update-alternatives --config default.plymouth：
There are 3 choices for the alternative default.plymouth (providing /usr/share/plymouth/themes/default.plymouth).
Selection Path Priority Status
------------------------------------------------------------
* 0 /usr/share/plymouth/themes/ubuntu-mate-logo/ubuntu-mate-logo.plymouth 150 auto mode
1 /usr/share/plymouth/themes/ubuntu-logo/ubuntu-logo.plymouth 100 manual mode
2 /usr/share/plymouth/themes/ubuntu-mate-logo/ubuntu-mate-logo-scale-2.plymouth 149 manual mode
3 /usr/share/plymouth/themes/ubuntu-mate-logo/ubuntu-mate-logo.plymouth 150 manual mode