Prepositions are among the most overworked words in the English language. Use the following guidelines to avoid committing two of the more common errors.
1) Avoid putting unnecessary prepositions at the end of sentences.
Example:
Incorrect: Where are the boys at?
Correct: Where are the boys?
Incorrect: Can I go with?
Correct: Can I go? or Can I go with you?
Incorrect: Where did that cat get to?
Correct: Where is the cat?
2) In formal writing and business communications, avoid putting the preposition at the end of a sentence.
Rewrite the sentence so that it has a correct prepositional phrase.
Avoid: They were not sure which city they were going to.
Better: They were not sure to which city they were going. (The preposition is now part of the phrase to which city.)
Avoid: Ask not whom the bell tolls for.
Better: Ask not for whom the bell tolls.