* Pronoun: A pronoun is a word that replaces a noun. Examples: *he*, *she*, *it*, *they*, *we*, *you*, *I*.
* Preposition: A preposition shows the relationship between a noun or pronoun and another word in the sentence. Examples: *on*, *in*, *under*, *around*, *to*, *from*.
* Conjunction: A conjunction joins words, phrases, or clauses. Examples: *and*, *but*, *or*, *because*, *since*, *although*.
Why the term "pronoun preposition conjunction" doesn't make sense:
* Pronouns and prepositions have different roles: Pronouns stand in for nouns, while prepositions show relationships. They don't combine to form a new grammatical category.
* Conjunctions connect elements: Conjunctions are used to join different parts of a sentence, but they don't describe a single word type.
Example to illustrate:
* Correct sentence: *He went to the store.*
* "He" is a pronoun (replacing a noun like "John").
* "to" is a preposition (showing the relationship between "He" and "store").
In summary: Pronouns, prepositions, and conjunctions are separate parts of speech with distinct functions in a sentence. They don't combine to form a new grammatical category.