isotope cow

例句：

1. 1.The isotopes in the sample were analyzed to determine its composition.
   对样本中的同位素进行了分析以确定其组成。
2. 2.The isotopes of carbon-14 are used to date ancient fossils.
   碳-14的同位素被用于测定古代化石的年龄。
3. 3. The isotopes of nitrogen and oxygen are found in all living organisms.
   氮和氧的同位素存在于所有生命体中。