Of course, it was an element the periodic table let us to expect existed before anyone had found it or made it.(当然，它在被人发现或制造前，就是一种元素周期表使得我们期待其存在的元素。)
Why do we call it the Periodic Table?(为什么我们叫它周期表？)
Bone growth in reptiles is periodic in nature, producing a series of concentric rings in the bone, not unlike the growth rings of a tree.(爬行动物的骨骼生长在本质上是周期性的，在骨头上产生一系列的同心圆，就像树木的年轮一样。)
The bordereaux are periodic reports or settlement statements.(业务报表是定期报告或和解声明。)
Periodic changes in Earth's orbit could affect Earth's climate.(地球轨道的周期性变化会影响地球的气候。)
Periodic checks are carried out on the equipment.(设备定期进行检查。)
Consequently, the timing and rhythms of biological functions must closely match periodic events like the solar day, the tides, the lunar cycle, and the seasons.(因此，生物功能的时间和节奏必须与太阳日、潮汐、月球周期和季节等周期性事件密切契合。)
Yet Rampino and others question one of the traditionalists' basic assumption: the periodic occurrence of glaciation throughout Earth's history.(然而，兰皮诺和其他人对传统主义者的一个基本假设提出了质疑：在整个地球历史中，冰川期是周期性发生的。)
In places, the water table is declining at a rate of a meter a year, necessitating the periodic deepening of wells and the use of ever-more-powerful pumps.(在一些地方，水位正以每年一米的速度下降，需要定期加深井并使用更强大的水泵。)
Let's continue our discussion now by talking about orbits, especially those of the so-called periodic-orbit comets.(现在我们继续讨论，谈谈轨道，特别是那些所谓的周期轨道彗星。)
