安装synaptics失败

[EarlHwong]

ubuntu 14.04
安装时没有预装synaptics

代码： 全选

sudo apt-get install xserver-xorg-input-synaptics

显示

代码： 全选

earl@earl-Ubuntu:~$ sudo apt-get install xserver-xorg-input-synaptics
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:
 xserver-xorg-input-synaptics : Depends: xorg-input-abi-20
                                Depends: xserver-xorg-core (>= 2:1.14.99.902)
E: Unable to correct problems, you have held broken packages.

求解！！

[vickycq]

代码： 全选

sudo lshw -C display
dpkg --get-selections | grep hold
cat /etc/apt/sources.list
cat /etc/apt/sources.list.d/*
apt-cache policy xserver-xorg-core
aptitude why-not xserver-xorg-input-synaptics

把结果全部复制贴上来