试题题干
In （ ）drills, the students change a given structure in a way so that they are exposed to other similar structures, which also helps them have a deeper understanding of how the structures are formed and how they are used.
参考答案
正确答案：
试题解析
考查语法教学。在语法练习中，机械操练有两种常用方式：替换操练（substitution drills）和转换操练（transformation drills）。题干叙述内容属于转换操练。故选B。