Pairs; sets of two elements treated as a single unit.

由两个要素构成并被视作一体的成对事物。

Two people in an ongoing relationship; the dyadic relationship.

处于持续关系中的两个人；该二人关系本身。

Sets of two different pitch classes.

由两个不同音高类组成的集合。

Elements, atoms, or radicals with valence two.

化合价为二的元素、原子或基团。

Chromosome structures of two sister chromatids joined by a centromere.

由两个姐妹染色单体经着丝粒连接成的染色体结构。

Order-two, rank-one tensors, the outer product of two vectors.

二阶且秩为一的张量，即两个向量的外积。