pip install installation is very slow, the solution to the installation failure

Choose a mirror:
• Alibaba Cloud: https://mirrors.aliyun.com/pypi/simple/
• Douban: https://pypi.douban.com/simple/
• Tsinghua University: https://pypi.tuna.tsinghua. edu.cn/simple/University of
Science and Technology of China http://pypi.mirrors.ustc.edu.cn/simple/

For example: install Django with the -i option and update soon