Which of the following is NOT one of the characteristics of idioms? （ ）
A、The part of speech of each element in an idiom is very important.
B、The constituents of idioms can’t be replaced.
C、The word order in an idiom can’t be changed.
D、An idiom functions as one word.
【正确答案】：A
【题目解析】：习语的特点包括语义统一性，结构稳定性，习语分类。
