试题题干
Fill in each of the following blanks with a word or an expression.
A 
study is concerned with the historical development of a language over a period of time.
参考答案
试题解析
A diachronic study is concerned with the historical development of a language over a period of time. 历时性研究关注的是语言经过一定时间阶段所发生的历史变化。