无法在VS Code中进行调试

I'm new to VS Code, and is following the official tutorial to learn how to debug. However, it just won't work. First, the UI looks different. It shows "RUN".

与视频中显示“调试”的用户界面的外观相比。

另外，我添加了一个断点并单击绿色的“开始”按钮，它从未停止过。

Here's the launch.json file:

我应该怎么做才能使调试器正常工作？