isotope tag

例句：

1. 1.The isotopes were used to trace the origin of the water.
   这些同位素被用来追踪水的源头。
2. 2. The team used isotopes to study the movement of the earth's crust.
   团队使用同位素来研究地球地壳的运动。
3. 3.The isotopes were used to determine the age of the rocks.
   这些同位素被用来确定岩石的年龄。