1. The chemical composition of stars can help us determine their age.
恒星的化学成分可以帮助我们确定它们的年龄。
2. The chemical composition of water is H₂O.
水的化学成分是H₂O。
3. Scientists studied the chemical composition of the rock.
科学家研究了岩石的化学成分。
4. Chemical composition analysis is an important part of scientific research.
化学成分分析是科学研究的重要部分。
5. The chemical compositions of different substances vary.
不同物质的化学成分各不相同。