烧瓶运行错误，显示未找到运行命令

Question

我正在尝试运行一个项目，它昨天已在工作，但现在正在显示。

(flaskenv) pravin@pravin-Aspire-A315-31:~/PycharmProjects/flask_crud_apis_Fix$ flask run
 * Serving Flask app "api.py"
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
/home/pravin/Desktop/flaskenv/lib/python3.6/site-packages/flask_sqlalchemy/__init__.py:794: FSADeprecationWarning: SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and will be disabled by default in the future.  Set it to True or False to suppress this warning.
  'SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and '
usage: flask [global_opts] cmd1 [cmd1_opts] [cmd2 [cmd2_opts] ...]
   or: flask --help [cmd1 cmd2 ...]
   or: flask --help-commands
   or: flask cmd --help

error: invalid command 'run'

我正在使用虚拟环境，之前也使用过。