这项研究侧重于该山脉历经数百万年的地质形成过程。

The study focuses on the geological ___formation of the mountain range over millions of years.

水蒸气的冷却和凝结导致了云层的形成。

The cooling and condensation of water vapor leads to the ___formation of clouds.

科学家们在显微镜下观察了晶体的形成。

Scientists observed the ___formation of a crystal under the microscope.