triennium

例句：

1. 1.The triennium was a time of great change and growth for the country.
   三世纪是该国经历巨大变革和增长的时期。
2. 2.During the triennium, the economy grew rapidly.
   在三世纪期间，经济迅速增长。
3. 3. The triennium is often remembered as a time of great cultural achievements.
   三世纪通常被记住为文化成就的时代。