Rome's power reached its zenith under the emperor Trajan.
罗马帝国的势力在图雷真皇帝的统治下达到顶峰。
A point on the celestial sphere directly below the observer, diametrically opposite the zenith.
天底天球上，在观测者垂直向下的一点，与天顶完全相对
He has reached the zenith of his career.
他已经达到了他事业的顶峰。
