Here's why:
* Prepositions show the relationship between a noun or pronoun and another word in the sentence. They usually indicate location, time, or direction. Examples: *in, on, under, before, after, to, from*.
* Conjunctions connect words, phrases, or clauses. They can be coordinating (and, but, or, so) or subordinating (because, although, while, if).
"Except" is a coordinating conjunction that means "but" or "excluding." It joins two parts of a sentence that contrast with each other.
Example:
* All the students were excited about the trip except John.
Here, "except" joins the phrases "all the students" and "John," indicating that John was not excited about the trip.
Let me know if you have any other grammar questions!