Final answer:
In the sentence, the three prepositional phrases are 'several days in the library', 'for their work', and 'according to the librarian', each serving to modify different elements and providing additional details.
Step-by-step explanation:
In the sentence provided, the three prepositional phrases are:
- 'several days in the library'
- 'for their work'
- 'according to the librarian'
A prepositional phrase typically consists of a preposition followed by a noun or pronoun that serves as the object of the preposition. These phrases can act as adjectives, adverbs, or noun phrases and modify different elements within a sentence. In our examples, 'several days in the library' modifies the amount of time spent, 'for their work' explains the purpose, and 'according to the librarian' provides the source of information. These phrases give additional details about the actions, reasons, or conditions in the sentence.
It's important to note that a prepositional phrase can contain other phrases within it, and it can act as an adverbial as indicated in the first example. An adverbial prepositional phrase modifies a verb, an adjective, or another adverb by providing more information such as time, place, cause, manner, or degree.