当尝试在 Ubuntu 15.10 上使用以下方式安装 KDE Plasma（Kubuntu 桌面）时
sudo apt-get install kubuntu-desktop
然后出现这个错误，
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:
kubuntu-desktop : Depends: kinfocenter but it is not going to be installed
Depends: kwin
Depends: plasma-desktop but it is not going to be installed
Depends: powerdevil but it is not going to be installed
Depends: sddm-theme-breeze but it is not going to be installed
Depends: software-properties-kde but it is not going to be installed
Recommends: apport-kde but it is not going to be installed
Recommends: apturl-kde but it is not going to be installed
Recommends: gwenview but it is not going to be installed
Recommends: kate but it is not going to be installed
Recommends: kde-telepathy but it is not going to be installed
Recommends: kdeconnect-plasma but it is not going to be installed
Recommends: kscreen but it is not going to be installed
Recommends: kubuntu-driver-manager but it is not going to be installed
Recommends: kubuntu-notification-helper but it is not going to be installed
Recommends: kwin-addons but it is not going to be installed
Recommends: milou but it is not going to be installed
Recommends: muon-discover but it is not going to be installed
Recommends: muon-notifier but it is not going to be installed
Recommends: pam-kwallet5 but it is not going to be installed
Recommends: plasma-nm but it is not going to be installed
Recommends: plasma-wallpapers-addons but it is not going to be installed
Recommends: plasma-widget-kimpanel but it is not going to be installed
Recommends: plasma-widgets-addons but it is not going to be installed
Recommends: print-manager but it is not going to be installed
E: Unable to correct problems, you have held broken packages如何解决这个问题？请帮帮我。谢谢。