Prepositions

The Basics:                 Prepositions are difficult to define but, fortunately, not so difficult to understand.  They tell

the “position” of people or things in relation to where other people or things are located.  They can show relationships between objects in space (where one thing is in relation to another), and they can show relationships in time (when an event occurred in relation to another event).  

Examples (space relationship):  The paper is under the book.

                                                    My mother walked through the door.

Examples (time relationship):  I left the graduation ceremony before the final speech.

                                                  Jacky felt sick during the plane ride.

Prepositions begin grammatical structures called Prepositional Phrases.  Prepositional Phrases always begin with a preposition and end with a noun or pronoun which is the preposition’s object (the word that the preposition is in relation to).  In addition to the preposition and its object, the prepositional phrase also contains those words that modify the preposition’s object.  In the following examples, the prepositions are printed in italics, the prepositions’ objects (what the prepositions are in relation to) are printed in bold, and the entire prepositional phrase is in parentheses.

            Example:  The ball bounced (over the fence).

            Example:  We went to dinner (after the football game).

Why is it important to identify Prepositional Phrases?

We use prepositional phrases all the time in our writing without even realizing it.  Being conscious of how we use prepositional phrases can be extremely useful when writing and editing sentences.  Look at how many prepositional phrases are in the following sentence.  

Example:  We will leave (on our trip) (to Las Vegas) (before nightfall) (by 5:00).

There are four prepositional phrases just in this short sentence.  Although prepositional phrases are critical to conveying meaning, overusing prepositional phrases can sometimes make a sentence wordy and confusing.  Thus, becoming conscious of the use of prepositional phrases can help the writer determine if they are in fact necessary.  

Identifying prepositional phrases is perhaps most important to beginning writers because, by doing so, they can more easily identify the main subject and verb of a sentence, a skill which is critical to writing grammatically correct sentences.  Here is the trick: the true subject and verb of a sentence can never appear within a prepositional phrase.  Thus, by identifying and highlighting the prepositional phrases in a sentence, a writer can narrow down the number of possible words from which to identify the subject and verb.  It is a strategy of finding the subject and verb through a process of elimination.  

For example, in the sentence “That group of boys plays roughly,” one might think that the subject of the sentence is “boys,” but this is incorrect.  The subject is actually “group,” and we can see this if we highlight the prepositional phrases which, as we know, cannot contain the true subject or verb of the sentence: “That group (of boys) plays roughly.”  Or we can look at the long example above: “We will leave (on our trip) (to Las Vegas) (before nightfall) (by 5:00).”  If we eliminate the prepositional phrases in this sentence, we are left with only three words from which to choose the subject and verb—“we,” “will,” and “leave.”  Obviously this makes subject/verb identification much easier.  

  

                                 

Be Careful!    This trick only works if the writer correctly identifies the prepositional phrases.  If the writer wrongly identifies the prepositional phrases, he or she can easily misidentify the subject and verb of a sentence.  Some words that function as prepositions can function in other ways as well, so don’t be fooled!  Look at the following rules to ensure you don’t misidentify prepositions. 

Rule 1:  Do not confuse prepositions with subordinating conjunctions.  Some words that function as  prepositions can also function as subordinating conjunctions.  Instead of introducing a prepositional phrase that cannot contain a sentence’s subject or verb, subordinating conjunctions introduce dependent clauses which do contain a true subject and verb.  Compare the following two examples.  They appear to be similar, but the first contains a prepositional phase and the second does not:  “We went to dinner after the football game” contains a prepositional phrase as discussed earlier in this handout. Now look at the following sentence in which “after” change roles from a preposition to a subordinating conjunction: “We went to dinner after we went to the football game.” The word “after” no longer functions as a preposition introducing a prepositional phrase; instead, it functions as a conjunction connecting the two clauses “we went to dinner” and “we went to the football game.”  This is important because, rather than introducing a prepositional phrase which contains no subject or verb, “after” introduces a dependent clause which does contain a subject and verb.  

Rule 2:  A Preposition must always have an object.  Remember, there is no such thing as a  preposition without an object which is always a noun.  So when a word that is commonly thought of as a preposition appears in a sentence and does not have an object, it is functioning as some other part of speech, usually an adjective or adverb.  

            Example:  I’ve seen that movie before.

            “Before,” as we have seen, can function as a preposition; however, in this example it has no object and thus cannot be a preposition.  For “before” to be a preposition, the sentence would need to answer the question “before what?” (e.g. “I saw that movie before Christmas”).

            Keeping this rule in mind should keep you from making common mistakes when identifying prepositions and prepositional phrases.  

            Here is a list of common prepositions that show positions in space:

  about behind in outside  above below inside over  across beneath into past

 against beside near through  along between off to

            among beyond            on        toward

            Here is a list of common prepositions that can show positions in time:

  before throughout past within  after by until in

            since    at         during for

             

            Here are a few of the most common prepositions that do not fit neatly into the space or time category:              

             of        as         like

                         

Revised 2/5/03