Pre – Positional Is Where a Preposition Lives

[found on grammar.about.com]

“Like adjectives and adverbs, prepositional phrases add meaning to the nouns and verbs in our sentences. There are two prepositional phrases in the following sentence:

The steamy air in the kitchen reeked of stale food.

The first prepositional phrase–in the kitchen–modifies the noun air; the second–of stale food–modifies the verb reeked. The two phrases provide information that helps us understand the sentence.

The Two Parts of a Prepositional Phrase
A prepositional phrase has two basic parts: a prepositionplus a noun or a pronoun that serves as the object of the preposition. A preposition is a word that shows howa noun or a pronoun is related to another word in a sentence. The common prepositions are listed in the table at the bottom of this page.

Building Sentences with Prepositional Phrases
Prepositional phrases often do more than just add minor details to a sentence: they may be needed for a sentence to make sense. Consider the vagueness of this sentence without prepositional phrases:

The workers gather a rich variety and distribute it.

Now see how the sentence comes into focus when we add prepositional phrases:

From many sources, the workers at the Community Food Bank gather a rich variety of surplus and unsalable food and distribute it to soup kitchens, day-care centers, and homes for the elderly.

Notice how these added prepositional phrases give us more information about certain nouns and verbs in the sentence:

Which workers?
The workers at the Community Food Bank.
What did they gather?
A rich variety of surplus and unsalable food.
Where did they gather the food?
From many sources.
Who did they distribute it to?
To soup kitchens, day-care centers, and homes for the elderly.

Like the other simple modifiers, prepositional phrases are not merely ornaments; they add details that can help us understand a sentence.

PRACTICE: Building with Simple Modifiers
Use adjectives, adverbs, and prepositional phrases to expand the sentence below. Add details that answer the questions in parentheses and make the sentence more interesting and informative.

Jenny stood, raised her shotgun, aimed, and fired.
(Where did Jenny stand? How did she aim? What did she fire at?)

There are, of course, no single correct answers to the questions in parentheses. Sentence-expanding exercises such as this one encourage you to use your imagination to build original sentences.”