[单选题]Which of the following is NOT one of the characteristics of idiom

The part of speech of each element in an idiom is very important.

The constituents of idioms can’t be replaced.

The word order in an idiom can’t be changed.

An idiom functions as one word.

many idioms are grammatically unanalysable

the word order of idioms cannot be inverted or changed

the structure of an idiom is to a large extent unchangeable

the constituents of an idiom cannot be deleted or added to

[单选题]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.