sempiternal

古代天文学家相信天穹是永恒的，在人类时间之前与之后都不曾改变。

Ancient astronomers believed the heavens were ___sempiternal, existing unchanged before and beyond human time.

冰川永恒的运动在数百万年间将山脉研磨为尘土。

The glacier's ___sempiternal movement ground the mountains into dust over millions of years.

数学家们将算术法则描述为永恒真理，任何发现都无法推翻。

Mathematicians describe the laws of arithmetic as ___sempiternal truths that no discovery could overturn.