Here's why:
* Gerund phrases are verb forms ending in "-ing" that act as nouns (e.g., "Swimming is my favorite activity").
* Participial phrases are verb forms ending in "-ing" or "-ed" that act as adjectives (e.g., "The laughing child" or "The broken vase").
* Infinitive phrases are verb forms starting with "to" (e.g., "to run a marathon").
* Prepositional phrases are groups of words starting with a preposition (e.g., "on the table," "with a smile").
Prepositional phrases are not verb-related and don't function as verbs, nouns, or adjectives. They primarily show relationships between words in a sentence.