Lip service cannot be turned into mouth service,which indicates “_____"

Lip service cannot be turned into mouth service,which indicates “_____"

A.the constituents of idioms cannot be replaced

B.the word order cannot be inverted or changed

C.the various words that make up the idioms have lost their individual identities

D.the constituents of an idiom cannot be deleted or added to, not even an article

正确答案是A