Here's why:
* Prepositional phrase: A prepositional phrase starts with a preposition (like "of", "in", "on", etc.) and ends with a noun or pronoun (the object of the preposition).
* Partitive phrase: A partitive phrase indicates a part of a whole, often using "of" to connect the part to the whole. It acts as an adjective to modify a noun.
Example:
* "The mayor of the town" - "of the town" describes which mayor we're talking about, acting like an adjective for "mayor". It's a partitive phrase.
* "The mayor in the town" - "in the town" tells us where the mayor is, acting like an adverbial phrase modifying "mayor". This is a prepositional phrase.
To sum up: While "of the town" uses the preposition "of," its function is to identify a specific part of the larger whole ("the town"), making it a partitive phrase.