Flask Python框架安装

我一直在尝试安装和运行它，但是它不起作用。

我想首先在我的工作文件夹中创建一个虚拟环境，然后我能够在python-scripts文件夹中安装virtualenv。我在Windows中使用cmd行。

C:\Users\ADMIN\python\Scripts>pip install virtualenv
Requirement already satisfied: virtualenv in c:\users\admin\python\lib\site-packages (16.0.0)
You are using pip version 10.0.1, however version 18.0 is available.
You should consider upgrading via the 'python -m pip install --upgrade pip' command.

C:\Users\ADMIN\python\Scripts>cd..

C:\Users\ADMIN\python>cd..

C:\Users\ADMIN>cd desktop

C:\Users\ADMIN\Desktop>cd flask_bookreview

C:\Users\ADMIN\Desktop\flask_bookreview>virtualenv flask
'virtualenv' is not recognized as an internal or external command,
operable program or batch file.