在 Ubuntu 16.04 中运行后apt-cache policy python，我得到了以下结果：python: Installed: 2.7.12-1，但我无法安装任何 python 包。我被这个错误困住了：
The following packages have unmet dependencies:
python-dev : Depends: python (= 2.7.11-1) but 2.7.12-1 is to be installed
python-setuptools : Depends: python-pkg-resources (= 20.7.0-1) but it is not going to be installed
Depends: python:any (< 2.8)
Depends: python:any (>= 2.7.5-5~)
E: Unable to correct problems, you have held broken packages.
结果sudo apt install python-pkg-resources
The following packages have unmet dependencies:
python-pkg-resources :
Depends: python:any (< 2.8)
Depends: python:any (>= 2.7.5-5~)
E: Unable to correct problems, you have held broken packages.