输入：pip install pillow
出现错误 Requirement already satisfied :pillow in f:\软件\python\lib\site-packages(7.1.1)
WARNING:You are using pip version 20.0.2:however. version 20.1 is available.
You should consider upgrading via the ‘f:\软件\python\python.exe -m pip install --upgrade pip’ command.
于是我升级pip : pip install --upgrade pip
又出错啦~~
重装pip : python -m ensurpip
然后升级pip : python -m pip install --upgrade pip
找到：解决办法：使用pip install 命令时指定安装路径
格式：pip install --target=目标路径 工具包名字
成功啦~~