covariant index

例句：

1. 1. The covariant index of the material is crucial for its strength and durability.
   材料的协变指数对其强度和耐久性至关重要。
2. 2. In the study of crystallography, the covariant index is used to describe the orientation of atoms in a crystal lattice.
   在晶体学研究中，协变指数用于描述晶体晶格中原子的取向。
3. 3. The covariant index can be calculated using specialized software that takes into account the material's properties and theexternal forces acting on it.
   可以使用专门软件计算协变指数，该软件考虑了材料的性质以及作用于它的外部力。