上网查了查，多数人是源的问题。文件如下：mert@A55:~$ sudo apt-get install mate-core
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:
mate-core : Depends: mate-control-center (>= 1.6.0) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
P.S. 由于之前装了apt-spy，所以我的源文件不是/etc/apt/sources.list而是/etc/apt/sources.list.d/apt-spy.list。mert@A55:~$ cat /etc/apt/sources.list.d/apt-spy.list
deb http://mirrors.ustc.edu.cn/debian wheezy main non-free contrib
deb http://mirrors.ustc.edu.cn/debian wheezy-proposed-updates main contrib non-free
deb-src http://mirrors.ustc.edu.cn/debian wheezy main non-free contrib
deb-src http://mirrors.ustc.edu.cn/debian wheezy-proposed-updates main contrib non-free
deb http://mirrors.ustc.edu.cn/debian-security wheezy/updates main contrib non-free
deb-src http://mirrors.ustc.edu.cn/debian-security wheezy/updates main contrib non-free
deb http://repo.mate-desktop.org/debian wheezy main
感觉我的源也没问题，没辙了，特此求助。