periodical

The library subscribes to several periodical publications covering different subjects.

用法提示：periodical 作定语修饰 publications，表示“定期出版的”。

It is important to make periodical checks of the smoke detectors at home.

用法提示：periodical 作定语修饰 checks，表示“周期性的/定期的”。

Staff receive periodical training sessions to update their skills.

用法提示：periodical 作定语修饰 training sessions，表示“定期发生的”。