Twenty Common Usage and Punctuation Errors

1. Missing comma after an introductory element

Use a comma after introductory phrases of three or four words.
Correct: When the concert was about to begin, the lights were dimmed.

2. Vague pronoun reference

Pronouns must refer to a specific antecedent (person, place, or thing).
Correct: I was certain I sealed the letter before I mailed it.

3. Missing comma in a compound sentence

Use a comma after and,or,nor,but,yet, and so when these words link independent clauses.
Correct: A prominent author suggested that writing well is always a challenge, yet he was able to publish twenty novels.
Incorrect: A prominent author suggested that writing well is always a challenge, he was able to publish twenty novels.

4. Wrong word

Be aware of the denotation and the connotation of words.
Correct: The students were afflicted with a mysterious illness.
Incorrect: The students were inflicted with a mysterious illness.

5. Missing commas with a nonessential (nonrestrictive) element

Nonessential modifiers can be removed from a sentence without affecting the meaning.
Correct: Darwin's most important work,On the Origin of the Species, was published after years of research.

6. Wrong or missing verb ending

Understand regular and irregular verb endings.
Correct: I was used to searching online.
Incorrect: I was use to searching online.

7. Incorrect or missing preposition

Correct: I applied to work at one of the world's major corporations.
Incorrect: I was not discouraged of trying to improve my grade.

8. Comma splice

Do not use a comma alone to link two independent clauses.
Correct: Nearly everyone has heard of Madame Curie, although I never heard of her husband.
Incorrect: A good financial planner explores all options, a poor financial planner conducts superficial research.

9. Missing or misplaced possessive apostrophe

Use apostrophe placement to signal singular or plural possession.
Correct: [many students] The students' computer lab is open until midnight.
Incorrect: [many students] The student's computer lab is open until midnight.

Correct: [one computer] The computer's keyboard was inoperable
Incorrect: [one computer] The computers keyboard was inoperable.

10. Unnecessary shift in tense

Choosing a tense signals the time of the action.
Correct: [simple past action] Rachel dropped her hat and then dropped her umbrella.
Incorrect: [simple past action] Rachel dropped her hat and was dropping her umbrella.

11. Unnecessary shift in pronoun

Maintain consistent pronoun use when referring to someone or something.
Correct: While you are visiting the museum, make sure you look at the Vermeer.
Incorrect: When one sees an accident, you are obliged to help.

12. Sentence fragment

All sentences should contain a complete subject and verb, either stated or implied.
Correct: The presidential inauguration is held in Washington, D.C.
Incorrect: Once the president is inaugurated.

13. Wrong tense or verb form

Verbs should precisely indicate when an action occurred. Use the correct form of an irregular verb.
Correct: When Sheila made the telephone call, Iris had died.
Incorrect: When Sheila made the telephone call, Iris died. [sequence of events is unclear]

14. Lack of subject-verb agreement

Change the verb form depending on whether the subject is singular or plural.
Correct: The examination was held at the appointed time.
Incorrect: The examination were held at the appointed time.

15. Missing comma in a series

Place commas after all words in a series except the last.
Correct: The syllabus included works by Shakespeare, Milton, and Cervantes.
Incorrect: The syllabus included works by Shakespeare Milton and Cervantes.
[Note: Newspaper and magazine articles often omit the comma after the next-to-last item in a series.]

16. Lack of agreement between pronoun and antecedent

Use singular pronouns to replace singular nouns and plural pronouns to replace plural nouns.
Correct: The players gloried in their win over the opponents. [plural-plural]
Incorrect: The player knew that their determination would help win the game over their rival. [singular-plural]

17. Unnecessary commas with a restrictive element

A restrictive element is essential to the basic meaning of the sentence. It is not set off from the rest of the sentence with commas.
Correct: The dog whose picture was shown on television last night pulled a child from a burning house.
Incorrect: The dog, whose picture was shown on television last night, pulled a child from a burning house.

18. Fused (run-on) sentence

Use end punctuation to separate independent clauses
Correct: David purchased two tickets for the performance. He had invited Anne.
Incorrect: David purchased two tickets for the performance happily he invited Anne.

19. Misplaced or dangling modifier

Every modifier(whether a word, phrase, or clause) should be as close as possible to the word it describes.
Correct: Pat showed her guests the pool that had recently been filled with water.
Incorrect: Pat showed the new pool to her guests that had just been filled with water.

20. Its/It's confusion

Use its (no apostrophe) as a possessive. Use it's (with apostrophe) as a contraction for it is.
Correct: It's possible I will meet you before class.
Incorrect: Its not over until its over.