1·If a change does not affect the food's chemical composition, we call it a physical change.
如果一种变化不影响食物的化学成分，那我们便称之为物理变化。
2·The chemical composition of rainfall changes slightly as raid clouds move.
当雨云移动时，降雨的化学成分略有变化。
3·The chemical composition of rainfall changes slightly as rain clouds move.
降雨的化学成分随着雨云的移动而发生轻微变化。
4·Scientists had information about the shape of the domes but not about their chemical composition and origins.
科学家们掌握了关于圆顶形状的信息，但不清楚它们的化学成分和起源相关的信息。
5·We know they smear a liquid on the tube, but we don't know where they secrete it from or what its chemical composition is.
我们知道它们在管上涂抹了一种液体，但我们不知道它们从哪里分泌出这种液体，也不知道它的化学成分是什么。
6·Ir is found in high concentrations in some meteorites, in which the solar system's original chemical composition is preserved.
人们发现，在一些保存着太阳系原始化学成分的陨石中，铱元素的含量很高。
7·Samples recovered from the expedition revealed important differences in chemical composition and fossil distribution among the sediment layers.
探险队采集的样品揭示了沉积物层之间化学成分及化石分布上的重大差异。
8·When you analyze this light, you can figure out their distance from the Earth, and identify what they are made of, determine their chemical composition.
当你分析这些光的时候，你可以计算出它们与地球的距离，并确定它们由什么构成，查明它们的化学成分。
9·Each pattern stands for a distinct chemical element, and so different sets or patterns of spectral lines mean that the star has a different chemical composition.
每一种样式代表一种不同的化学元素，所以光谱线的不同集合或模式意味着这颗恒星有不同的化学成分。
10·The answer to this riddle lies in the metabolic activity of early photosynthetic life-forms that slowly but surely transformed the chemical composition of Earth's atmosphere.
这个谜题的答案在于早期光合生命形式的新陈代谢活动，这种活动缓慢但一定改变了地球大气的化学成分。