我第一次使用flask和python尝试创建Web应用程序。我在Windows
10上使用Cygwin；由于某些原因，即使我已经使用pip成功安装了flask：

$ pip install flask
Requirement already satisfied (use --upgrade to upgrade): flask in c:\python34\l                                                                                                                ib\site-packages
Requirement already satisfied (use --upgrade to upgrade): click>=2.0 in c:\pytho                                                                                                                n34\lib\site-packages (from flask)
Requirement already satisfied (use --upgrade to upgrade): Jinja2>=2.4 in c:\pyth                                                                                                                on34\lib\site-packages (from flask)
Requirement already satisfied (use --upgrade to upgrade): itsdangerous>=0.21 in                                                                                                                 c:\python34\lib\site-packages (from flask)
Requirement already satisfied (use --upgrade to upgrade): Werkzeug>=0.7 in c:\py                                                                                                                thon34\lib\site-packages (from flask)
Requirement already satisfied (use --upgrade to upgrade): MarkupSafe>=0.23 in c:                                                                                                                \python34\lib\site-packages (from Jinja2>=2.4->flask)
You are using pip version 7.1.2, however version 9.0.1 is available.
You should consider upgrading via the 'python -m pip install --upgrade pip' comm                                                                                                             and.

运行python app.py时仍然出现此错误：

$ python app.py
Traceback (most recent call last):
  File "app.py", line 1, in <module>
    from flask import Flask
ImportError: No module named flask

有任何想法吗？对不起，如果这是一个愚蠢的问题，这是很新的。