1. Steam condenses into water when it cools. 蒸汽冷却时凝结为水。
2. When this mixture cools, the result is of course glass. 混合物冷却后，其成果当然是玻璃了。
3. Then it snows because as the air rises, it cools off and loses its capacity to hold water vapor. 然后就会下雪，因为当空气上升时，它就会冷却并失去保持水蒸气的能力。
4. The physicist Fabian reasoned that as intergalactic gas cools, the cooler gas shrinks inward toward the center of the galaxy. 物理学家费边推断，当星系间的气体冷却时，较冷的气体向星系中心收缩。
5. The Romans observed that, when volcanic ash mixes with water and then cools, it gets extremely hard and almost impossible to break up. 罗马人观察到，当火山灰与水混合然后冷却，火山灰变得非常坚硬，几乎不可能分解。
