periodically
01
定期地，偶尔
now and then or from time to time
例子
The professor periodically updates the syllabus, adding new readings when relevant research emerges.
教授定期更新教学大纲，在相关研究出现时添加新的阅读材料。
The antique clock chimes periodically.
古董钟定期鸣响。
例子
The magazine is published periodically, with new issues every month.
该杂志定期出版，每月都有新刊。
The system performs backups periodically to prevent data loss.
系统定期执行备份以防止数据丢失。
