Analyze and comment on the following.Comment on the sentence："structural stability of idioms is absolutely unchangeable” and explain the reasons.

Analyze and comment on the following.Comment on the sentence："structural stability of idioms is absolutely unchangeable” and explain the reasons.

(L)THIS STATEMENT IS NOT TRUE.
(2)CHARACTERIZED BY SEMANTIC UNITY AND STRUCTURAL STABILITY，IDIOMS DO NOT ALLOW CHANGES AS A RULE. BUT STRUCTURAL STABILITY IS NOT ABSOLUTE. WHEN IDIOMS ARE USED IN ACTUAL CONTEXT, THEY DO EXPERIENCE GRAMMATICAL CHANGES SUCH AS DIFFERENT FORMS OF VERBS, AGREEMENT OF PERSONAL PRONOUNS AND NUMBER AND SO ON.
(3)OCCASIONALLY, WE MAY FIND CHANGES IN CONSTITUENTS OF IDIOMS：ADDITION, DELETION, REPLACEMENT, POSITION-SHIFTING, DISMEMBERING, ETC.