遇到的问题：安装python3时默认已安装pip，但cmd下无法使用pip install XX，报错
输入批评升级命令后，即可正常使用。
pip升级：
cmd下输入命令：
C:\Users\panda wanna fat>python3 -m pip install -U pip
Collecting pip
Downloading https://files.pythonhosted.org/packages/0f/74/ecd13431bcc456ed390b44c8a6e917c1820365cbebcb6a8974d1cd045ab4/pip-10.0.1-py2.py3-none-any.whl (1.3MB)
100% |████████████████████████████████| 1.3MB 16kB/s
Installing collected packages: pip
Found existing installation: pip 9.0.3
Uninstalling pip-9.0.3:
Successfully uninstalled pip-9.0.3
Successfully installed pip-10.0.1
安装requests模块：
C:\Users\panda wanna fat>pip install requests
Collecting requests
Downloading https://files.pythonhosted.org/packages/49/df/50aa1999ab9bde74656c2919d9c0c085fd2b3775fd3eca826012bef76d8c/requests-2.18.4-py2.py3-none-any.whl (88kB)
100% |████████████████████████████████| 92kB 136kB/s
Collecting urllib3<1.23,>=1.21.1 (from requests)
Downloading https://files.pythonhosted.org/packages/63/cb/6965947c13a94236f6d4b8223e21beb4d576dc72e8130bd7880f600839b8/urllib3-1.22-py2.py3-none-any.whl (132kB)
100% |████████████████████████████████| 133kB 233kB/s
Collecting chardet<3.1.0,>=3.0.2 (from requests)
Downloading https://files.pythonhosted.org/packages/bc/a9/01ffebfb562e4274b6487b4bb1ddec7ca55ec7510b22e4c51f14098443b8/chardet-3.0.4-py2.py3-none-any.whl (133kB)
100% |████████████████████████████████| 143kB 243kB/s
Collecting certifi>=2017.4.17 (from requests)
Downloading https://files.pythonhosted.org/packages/7c/e6/92ad559b7192d846975fc916b65f667c7b8c3a32bea7372340bfe9a15fa5/certifi-2018.4.16-py2.py3-none-any.whl (150kB)
100% |████████████████████████████████| 153kB 489kB/s
Collecting idna<2.7,>=2.5 (from requests)
Downloading https://files.pythonhosted.org/packages/27/cc/6dd9a3869f15c2edfab863b992838277279ce92663d334df9ecf5106f5c6/idna-2.6-py2.py3-none-any.whl (56kB)
100% |████████████████████████████████| 61kB 1.9MB/s
Installing collected packages: urllib3, chardet, certifi, idna, requests
The script chardetect.exe is installed in 'c:\python36\Scripts' which is not on PATH.
Consider adding this directory to PATH or, if you prefer to suppress this warning, use --no-warn-script-location.
Successfully installed certifi-2018.4.16 chardet-3.0.4 idna-2.6 requests-2.18.4 urllib3-1.22