Prepositional phrases modify nouns or verbs by providing additional information through a preposition and an object, such as 'over the mantelpiece.'
Prepositional phrases are groups of words that act as adjectives or adverbs, modifying nouns or verbs. They consist of a preposition and an object of the preposition. In the sentence provided, 'over the mantelpiece' is the prepositional phrase as it starts with the preposition 'over' and describes the location of the old painting.
https://brainly.com/question/34125032