The idiom tit for tat is not to be turned into tat for tit. This shows that ______.
A、many idioms are grammatically unanalysable
B、the word order ofidioms cannot be inverted or changed
C、the meaning of an idiom is to a large extent unchangeable
D、the constituents ofan idiom cannot be deleted or added to
【正确答案】：B
【题目解析】：从题干看，这道题考查的是习语的特点，即习语的结构相对稳定，所以不能交换两个词的顺序。见课本第163页。
