Here's why:
* Idioms are fixed expressions: Idioms are phrases with a meaning that is different from the literal meaning of the words. They are used as a single unit, and their meaning is often figurative. For example, "kick the bucket" means "to die," but it doesn't literally mean kicking a bucket.
* Adverbs modify verbs, adjectives, or other adverbs: Adverbs tell us how, when, where, or to what extent something is done. They provide additional information about the verb, adjective, or other adverb they modify. For example, "quickly," "happily," and "very" are adverbs.
While idioms can sometimes modify verbs, they do so in a different way than adverbs:
* Idioms act as a single unit: They don't modify a verb directly; they provide a specific meaning as a whole.
* Adverbs are individual words or phrases: They directly modify the word they are attached to.
Example:
* Idiom: "He kicked the bucket last night." (The idiom "kicked the bucket" acts as a single unit, conveying the meaning of death.)
* Adverb: "He died quickly." (The adverb "quickly" modifies the verb "died.")
In conclusion, idioms and adverbs are different types of linguistic units with distinct functions. While idioms can sometimes modify verbs, they do so in a different way than adverbs.