1. The ancient Romans held the lustrum every five years to purify the city.(古罗马人每五年举行一次lustrum来净化城市。)
2. The president's term lasted for a lustrum, during which many significant reforms were implemented.(总统的任期为五年,期间实施了许多重要的改革。)
3. The book tells the story of the country's development over the course of a lustrum.(这本书讲述了一个国家在五年期间的发展故事。)