·当在ununtu 子系统中安装 pip (sudo apt-get install python3-pip) 时报错：
    Reading package lists... Done
    uilding dependency tree       
    Reading state information... Done
    E: Unable to locate package ****

    解决：
    更新apt库:
        sudo apt-get update
        sudo apt-get upgrade
    

·安装cython 时报错:
     WARNING: The scripts cygdb, cython and cythonize are installed in '/home/xiaowei/.local/bin' which is not on PATH.
  Consider adding this directory to PATH or, if you prefer to suppress this warning, use --no-warn-script-location.

    解决:
    pip3 install --user cython
    
    或:
     sudo pip install Cython --install-option="--no-cython-compile"