Sentence Diagramming: Flashcard 7
A preposition is an uninflected word* that requires an object (a noun, a pronoun, or the equivalent) for completion. A popular definition of a preposition is "a word that shows anywhere a mouse can go." And indeed, words like over, under, on, up, to, around, and through (to name only some of the possibilities) are prepositions; however, many prepositions have nothing to do with where a mouse might go, e.g., with, for, about (in the sense of "concerning"), besides, since, of, against, and without

There are also phrasal prepositions, i.e., prepositions that consist of more than one word, such as out of, because of, and as for.

A prepositional phrase consists of a preposition and its object** (including article and adjectives). Adverbial prepositional phrases modify words that adverbs can modify (verbs, adjectives, adverbs); adjectival prepositional phrases modify words that adjectives can modify (nouns and pronouns).

As you make your way through these flashcards, you may wish to refer to a section of my website that deals with terminology,

On the right is a diagram of the sentence "She was traveling with some girls in her class." The phrases with some girls and in her class are prepositional phrases. The words with and in are prepositions; the words girls and class are objects of prepositions. The prepositional phrase with some girls is adverbial because it modifies a verb. The prepositional phrase in her class is adjectival because it modifies a noun. The structure on which a prepositional phrase is diagrammed is the same as the structure on which an indirect object is diagrammed. Whereas the diagonal line connecting the indirect object line with the base line is empty in the diagram of an indirect object, it is occupied by a preposition in the diagram of a prepositional phrase. Flashcard 8: adverbial objectives. 

* Verbs are inflected (changed) to show such things as tense and number, nouns and pronouns are inflected to show number and case, and adjectives and adverbs are inflected to show degrees of comparison. 

** Phrases and clauses can function as objects of prepositions. More on this later when we discuss gerund phrases and noun clauses .

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