Pronouns are words that replace nouns (e.g., he, she, it, they, we, you, I).
Prepositions are words that show the relationship between a noun or pronoun and another word in the sentence. They usually indicate location, direction, time, or manner. Examples include: on, in, at, to, from, by, with, etc.
Here's why pronouns can't be prepositions:
* Grammatical function: Pronouns function as subjects, objects, or possessors, while prepositions show relationships between words.
* Meaning: Pronouns don't express the kind of spatial, temporal, or directional relationships that prepositions do.
Let me know if you have any other questions about grammar!