That " missing mass" in the nucleus, known as its mass defect, is actually present in the form of energy.

原子核中的“缺失质量” ，称为质量缺陷， 实际上以能量的形式存在。

If you paid attention, you learned how Einstein's famous formula helps us calculate the binding energy of a nucleus from its mass defect.

如果您留心观察，就会了解到爱因斯坦著名的公式如何帮助我们根据质量亏损计算原子核的结合能。