试题题干
Fill in each of the following blanks with a word or an expression.
A 
relation describes the vertical dimension of a language. It is a relation between comparable elements at a particular place in structures.
参考答案
试题解析
一个纵聚合关系描述了语言的垂直维度。它是结构中某一特定位置的可比元素之间的关系。