free isotope

例句：

1. 1. The study of free isotope is crucial for understanding the origins of life on Earth.
   研究自由同位素对于理解地球上生命的起源至关重要。
2. 2.Free isotope can be used to detect pollution in water sources.
   自由同位素可以用来检测水源中的污染。
3. 3.The research team discovered a new type of free isotope that could potentially help us understand the evolution of life.
   研究团队发现了一种新的自由同位素，这可能有助于我们理解生命的进化。