PyQt5安装

在线安装
1.pip3 install PyQt5
2.pip3 install PyQt5-sip
3.pip3 install PyQt5-tools

离线安装
1.PyQt5-5.11.3-5.11.2-cp35.cp36.cp37.cp38-none-win_amd64.whl，89.0Mb
2.PyQt5_sip-4.19.15-cp37-none-win_amd64.whl，50.5Kb
3.pyqt5_tools-5.11.3.1.4-cp37-none-win_amd64.whl，56.6Mb

PyQt5 designer程序位置
查找法：使用Everything搜索pyqt5_tools
即C:\Users\Erica\AppData\Local\Programs\Python\Python37\Lib\site-packages\pyqt5_tools\