A preposition shows the relationship between a noun or pronoun and another noun or pronoun. In the following examples, the italicized words are prepositions and the underlined words are objects of the prepositions.
The cat under the fence
The cat between the fence and the house
Everyone except the girl in the blue dress
A letter about us
When the object is a pronoun, remember that the pronoun should be in the objective case.
Recognizing prepositions
Prepositions aren't as obvious as nouns and verbs, so they are not always easy to recognize. Look for a word that establishes a relationship with another word. For example, in the previous phrases, how is cat related to fence? The cat is under the fence. How is Everyone related to the girl? The girl is left out of the group Everyone. How is girl related to dress? She is in it. Table 1 shows several words commonly used as prepositions.
Some prepositions, called compound prepositions, are made up of more than one word, such as according to, because of, in front of, instead of, in spite of, and next to.
Confusing use of prepositions
The unnecessary use of prepositions is a common error. Be careful not to use a preposition where it isn't needed.
Where have you been?
not Where have you been at?
Where is Nick going?
not Where is Nick going to?
Also, don't use two prepositions when you need only one.
Don't go near the water.
not Don't go near to the water.
The book fell off the table.
not The book fell off of the table.
Ending a sentence with a preposition can cause problems. The rule that a sentence should never end with a preposition is no longer strictly enforced. Still, many writers avoid ending sentences with prepositions. If you feel ending with a preposition makes a sentence sound more natural, do so and don't worry about it.
It is a comment to which I will not respond.
compared to It is a comment I will not respond to.
with which to write.
compared to I bought a pen to write with.