有时，当我安装东西时，我会收到如下错误：
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:
package1 : Depends: package2 (>= 1.8) but 1.7.5-1ubuntu1 is to be installed
E: Unable to correct problems, you have held broken packages.
我该如何解决这个问题？
package-management apt ppa dependencies software-installation
如何通过 将软件包降级到旧版本apt-get？
其他工具也可以接受，但apt-get最好使用。
从 10.04 升级到 12.04 后，我尝试安装不同的软件包。例如 ia32-libs 和 Skype (4.0)。
尝试安装这些时，我收到“无法纠正问题，您保存了损坏的软件包”错误消息。
命令的输出：
sudo apt-get install -f
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
运行后：
sudo dpkg --configure -a
foo@foo:~$ sudo apt-get install -f
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.