https://tensorflow.google.cn/install/pip#system-install
pip3 install --upgrade https://storage.googleapis.com/tensorflow/windows/cpu/tensorflow_cpu-2.3.0-cp37-cp37m-win_amd64.whl
安装 最新的 x64： vc_redist.x64.exe 不安装 ,可能 import tensorflow 报错
https://support.microsoft.com/zh-cn/topic/%E6%9C%80%E6%96%B0%E6%94%AF%E6%8C%81%E7%9A%84-visual-c-%E4%B8%8B%E8%BD%BD-2647da03-1eea-4433-9aff-95f26a218cc0