Their age can be found by looking at ratios of elements in them formed from radioactive decay.

它们的年龄可以通过观察由放射性衰变形成的元素的比例而发现。

Well, the blood that flows from your arm into that bag is whole blood, a mixture of cells and cell fragments called formed elements, along with water, and lots of dissolved molecules.

嗯，从你手臂流入袋子的血液是全血，细胞和细胞碎片的混合物，称为形成元素，还有水，和许多溶解的分子。