在状态进入和退出时可能执行其他动作。

Additional actions may be performed on state entry and exit.

youdao

这在退出时尤其常见。

This is especially common at exit time.

youdao

当计划退出时，美国将如何管理？

And how can the United States manage that when it's already planning an exit?

youdao

And most of these commands you don't actually need but this little caret symbol means control, so every keyboard these days has a control key so you hold that and hit X for instance to exit the program.

这里大多数命令你们都用不着,这个小插入符意味着控制，每个键盘都有一个控制键,譬如，当你敲入X时，就退出这个程序。

哈佛公开课 - 计算机科学课程节选