Error while creating sample Dash application

Hi Team,
I have created the sample app.py script. When I run the script I am getting below error. I have executed all the previous commands correctly. Not sure what went wrong. Please help.

Traceback (most recent call last):
File "D:\avocado_analytics\venv\app.py", line 1, in
import dash
ModuleNotFoundError: No module named 'dash'

从 app.py 第 1 行和 traceback 开始；检查运行它的是哪个环境，以及该环境是否能够导入示例应用程序的 Python 依赖项。示例应用程序能够在没有 ModuleNotFoundError 的情况下启动即表示完成；该 issue 没有指定要执行的测试或依赖项安装步骤。