Why is every time considered an adverbial phrase if not a preposition?

You're very close! "Every time" is an adverbial clause, not just a phrase. Here's why:

* Adverbial Clause: It functions like an adverb, modifying a verb, adjective, or another adverb. It tells us *when* something happens.

* Prepositional Phrase: A prepositional phrase usually starts with a preposition (like *in*, *on*, *at*, *with*, *by*, etc.) and includes a noun or pronoun. It generally describes location, time, or manner.

Example:

* "Every time I see her, I smile." ("Every time" modifies the verb "smile" by telling us *when* the smiling occurs.)

Let's look at why it's not a prepositional phrase:

* There's no preposition like "in" or "on" at the beginning of "every time."

* "Every" is an adjective modifying the noun "time."

In Summary:

"Every time" is an adverbial clause because it modifies a verb and tells us when something happens. It's not a prepositional phrase because it doesn't have a preposition at its head.