从极热的而干燥的岩石中提取热量，暴露出了一个更加困难的问题：必须击碎岩石以保证水的循环，而水必须是人工提供的。

Extracting heat from very hot, dry rocks presents a more difficult problem: the rocks must be fractured to permit the circulation of water, and the water must be provided artificially.

youdao

此外，“泰坦”的大气循环不是水的循环。

Moreover, Titan's atmospheric cycle is not a water cycle.

youdao

这个过程称为水的循环。

This process is called the water cycle.

youdao