The English language is full of all kinds of words that perform different functions. It can be difficult to distinguish which parts of a sentence indicate who is doing what where. Fortunately, prepositions can be the keys to unlocking the mechanics of English sentence structures.
So what are prepositions and what do they do? Think of prepositions as matchmakers. They are responsible for building relationships between other words in the sentence - specifically nouns. With, after, near, over, into, above, up, and to are some of the most frequently used prepositions, but there are many more.
One way to test to see if a word is a preposition or not is to imagine a bunny and a log, then see if the word in question can describe a relation between the bunny and log. The bunny can be on the log so "on" is a preposition. The bunny can be around the log, or by it, or in it too. These words give the picture in your mind direction as to how the bunny and the log exist in relation to each other. Remember that prepositions are matchmakers making relationships happen, so the bunny cannot be and the log; "and" suggests inclusion, not relationship.
Being able to decipher where the prepositions are in a sentence makes it easy to figure out the jobs of the words around it too. For example, if it is know that the bunny is behind the log and that "behind" is the preposition showing relationship between two nouns, it can be deducted that the bunny is the subject and the log is the object of the sentence because the preposition is describing the relationship between those two things.
Sometimes prepositions can have slightly more complex roles in the formulation of sentences than just bringing subjects and objects together. They are also commonly used as adjectives and adverbs (adjectives modify nouns and adverbs modify verbs). In these cases they are called prepositional phrases. A prepositional phrase is created by taking a preposition and linking it with a descriptive word to describe a noun or action happening in a sentence. When looking at the sentence "The bird flew with grace," the preposition "with" is paired with the word "grace" to form a prepositional phrase acting as an adverb to describe how the bird flew, the sentence's verb. In the sentence "The crowd was in shock," the prepositional phrase "in shock" directly describes the crowd. In this case the prepositional phrase acts as an adjective because it is describing the sentence's noun.
Prepositional phrases are easy to spot in sentences because they can be left out without turning the sentence into a fragment. The phrase "in shock" can be removed from the previous example and a coherent sentence comprised of the required subject and verb remains. The bird can still fly even if it is not with grace. Remembering that prepositions are all about describing relationship should make them easy to find and use in decoding sentence structures.
