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Top 20 Grammar Errors

Below is a list of the top Twenty GSU grammar errors. Click on each item to view a description of the error, as well as examples of incorrect and correct usage.

1. Missing commas to set off nonessential information

Commas are used to call attention to information that interrupts and does not alter the meaning of a sentence. If the sentence could provide a similar meaning without the extra information, then the commas help to illustrate that the extra information is there to provide nonessential rather than essential information.

CORRECT: John Smith, who won the writing contest, is in my class.

(The commas are necessary because "who won the writing contest" is only adding extra information about John Smith.)

INCORRECT: John Smith who won the writing contest is in my class.

(Commas around "who won the writing contest" are necessary because this phrase is intended to add only nonessential information about John Smith. Only if the information is essential are commas not needed. If more than one John Smith could be indicated, then the words "who won the writing contest" convey information essential to identify which John Smith is being referred to.)

2. Unnecessary commas to set off essential information

Commas are used to call attention to information that interrupts and does not alter the meaning of a sentence. If information is necessary to the meaning of a sentence, you should not set off this information in commas.

CORRECT: The student who won the writing contest is in my class.

(No commas are needed because "who won the writing contest" is necessary to understand the meaning of the sentence.)

INCORRECT: The student, who won the writing contest, is in my class.

(The commas setting off "who won the writing contest" are incorrect because the information is necessary to understand the meaning of the sentence.)

3. Missing comma before coordinating conjunction combining two independent clauses

Commas are used before coordinating conjunctions (for, and, nor, but, or, yet, so) if the coordinating conjunction is used to connect two independent sentences.

CORRECT: I wanted to go to the beach, but I couldn't afford to pay for a hotel room.

("I wanted to go to the beach" is a complete sentence as is "I couldn't afford to pay for a hotel room," so when they are joined with a coordinating conjunction, a comma should be placed before the conjunction.)

INCORRECT: I wanted to go to the beach but I couldn't afford to pay for a hotel room.

("I wanted to go to the beach" and "I couldn't afford to pay for a hotel room," are complete sentences joined with a coordinating conjunction, so a comma should be placed before the conjunction.)

CORRECT: I wanted to go to the beach but couldn't afford to pay for a hotel room.

("I wanted to go to the beach" is a complete sentence, but "couldn't afford to pay for the hotel room" is not a complete sentence, so it cannot stand alone and a comma should not be placed before the coordinating conjunction.)

4. Missing comma after introductory element

Commas help to call attention to opening ideas. A comma follows an introductory word, phrase, or clause.

CORRECT: Furthermore, everyone must wait thirty minutes after eating before they go swimming.

("Furthermore" is an introductory word and should be followed by a comma.)

INCORRECT: Furthermore everyone must wait thirty minutes after eating before they go swimming.

("Furthermore" is an introductory word and must be followed by a comma.)

CORRECT: From his perch in the top of the tree, John could see the neighbor's dog chewing on the children's missing Frisbee.

("From his perch in the top of the tree" is an introductory phrase and should be followed by a comma.)

CORRECT: Even though he knew that his brother would be angry over the lost Frisbee, John wasn't brave enough to go get it.

("Even though he knew that his brother would be angry over the lost Frisbee" is an introductory clause and should be followed by a comma.)

INCORRECT: Risking his life over a Frisbee, just didn't seem worth it.

("Risking his life over a Frisbee" is the subject of the sentence and should not be followed by a comma.)

5. Comma splice

A comma splice results when two independent clauses (two separate sentences) are joined with a comma rather than a period or semicolon. Writers often create comma splices when using transitional words, such as however, therefore, moreover, nevertheless, furthermore etc. These conjunctive adverbs seem like coordinating conjunctions (for, and, nor, or, but, yet, so), but they cannot be used in the same way. Therefore, these transitional words must either be used with a coordinating conjunction or set off by a period or a semicolon.

CORRECT: I had planned to enroll over the summer; however, I couldn't find any classes to fulfill my major requirements.

("However" is not a coordinating conjunction and must be preceded by a semicolon.)

INCORRECT: I had planned to enroll over the summer, however, I couldn't find any classes to fulfill my major requirements.

("However" is not a coordinating conjunction. A comma is not enough to join the two sentences)

CORRECT: I had planned to enroll over the summer, but I couldn't find any classes to fulfill my major requirements.

("But" is a coordinating conjunction, so the comma is enough to join the two sentences.)

INCORRECT: I; however, couldn't find any classes to fulfill my major requirements.

("However" in this sentence is not joining two sentences, so the semicolon is not needed here.)

6. Semicolon mistakes

A semicolon is used to separate two independent clauses (two separate sentences) that are closely related. Often, semicolons appear before transitional words, such as however, therefore, moreover, furthermore, nevertheless, etc. Semicolons can also be used to separate detailed items in a series. Experienced writers use semicolons infrequently.

CORRECT: John should enroll in an upper-level sociology class; he has fulfilled all of the prerequisites, and he is interested in the topic.

(The semicolon joins to two closely related sentences.)

INCORRECT: John should enroll in an upper-level sociology class; he has always wanted to join the swim club.

(The semicolon should not be used to join these two complete sentences because the sentences are not closely related.)

CORRECT: Many important members of the university attended the talk: Dr. Becker, the university president; Dr. Palms, the provost; and Dr. Stout, the dean of students.

(The semicolons are necessary to clearly divide the complex items in the list.)

INCORRECT: Many important members of the university attended the talk: Dr. Becker, the university president, Dr. Palms, the provost, and Dr. Stout, the dean of students.

(The items in this list contain commas, so semicolons are needed here to distinguish between the items.)

7. Possessives mistakes

Possessives illustrate ownership. Most of us know the rules of possession, but in the heat of the moment, while we're trying to get our ideas across, we either forget to add the possessive or we accidentally add the possessive to a word that should simply be plural.

CORRECT: Simon decided to join the men's group.

("Men" is already plural and only needs the "'s" to make it possessive.)

INCORRECT: Simon decided to join the mens' group.

(The "s" is not needed to make "men" plural. It is necessary to show possession and should come after the apostrophe)

CORRECT: The professor was concerned about the students' lack of interest.

(A plural noun ending in "s" only needs an apostrophe. Assuming "students" is plural in this sentence, no "s" is needed after the apostrophe.)

INCORRECT: The professor was concerned about the students's lack of interest.

("Students" is plural, so the "s" is not necessary after the apostrophe.)

8. Colon mistakes

A colon is used after a complete sentence to introduce a word, phrase, clause, list, or quotation. The colon indicates that what follows proves or explains the sentence before the colon.

CORRECT: Students choose GSU for three main reasons: its urban environment, its diverse student body, and its rigorous academic reputation.

(The list that follows the colon explains the complete sentence that precedes the colon.)

INCORRECT: Students choose GSU for: its urban environment, its diverse student body, and its rigorous academic reputation.

("Students choose GSU for" is not a complete sentence.)

9. Wrong word

Always choose the right word for the meaning you are trying to communicate. In writing, choosing a wrong word often occurs because one word sounds like another. "Their," "there," and " they're" sound the same, but have very different meanings. Contractions can also cause problems. "Should've" sounds like "should of," but the contraction is actually of the words "should have."

INCORRECT: You're semester is difficult because your taking too many classes.

("You're" means "you are" and "your" is possessive. Both are used incorrectly in this sentence. )

CORRECT: Your semester is difficult because you're taking too many classes.

("You're" and "your" are used correctly in this sentence.)

10. Lack of parallel structure

A list or comparison of equally significant ideas should use the same grammatical pattern. Unparallel structure can confuse a reader because different grammatical patterns within a list suggest that the items in a list don't belong together.

INCORRECT: Biology is my major because the subject is challenging, interesting, and excites me.

("excites me" does not have the same grammatical construction as the other items of the list, so it reads awkwardly. )

CORRECT: Biology is my major because the subject is challenging, interesting, and exciting.

(The three items in the list are equal and parallel in structure.)

INCORRECT: Biology is my major because the subject is challenging, interesting, and I plan on being a veterinarian.

("I plan on being a veterinarian" does not have the same grammatical construction as the other items of the list, so it reads awkwardly.)

CORRECT: I plan on being a veterinarian, so biology is my major. I also chose biology because I find it challenging and interesting.

("I plan on being a veterinarian" seems more significant than the other two items on the list, so it is appropriate to break the discussion into two sentences.)

11. Misplaced modifier

A modifier (a word, phrase, or clause that describes something else) goes next to the thing it modifies. A misplaced modifier can confuse a reader because the modifier appears to describe the wrong element in the sentence.

INCORRECT: Jamie ate a sandwich wearing a GSU sweatshirt.

("Wearing a GSU sweatshirt" modifies Jamie, so the phrase should be next to Jamie in the sentence. This sentence seems to suggest that the sandwich is wearing the sweatshirt.)

CORRECT: Wearing a GSU sweatshirt, Jamie ate a sandwich.

("Wearing a GSU sweatshirt" clearly modifies Jamie in this sentence.)

12. Dangling modifier

A modifier (a word, phrase, or clause that describes something else) must modify something in the sentence. A dangling modifier occurs when the element being modified is implied rather than stated.

INCORRECT: Turning the corner onto Peachtree Street, the park looked scenic.

(In this sentence, it is unclear who or what turned the corner. Grammatically, it seems that the park turned the corner.)

CORRECT: Turning the corner onto Peachtree Street, we noticed the park looked scenic.

("We" turned the corner, so "we" needs to be in the sentence.)

 

13. Split infinitives

An infinitive is "to" with a verb. A split infinitive is an infinitive with a word or words in between the "to" and the verb. Split infinitives do not necessarily cause confusion, but many readers disapprove.

INCORRECT: The professor asked the students to quickly take the quiz.

("To take" is an infinitive and should not be split by an adverb.)

CORRECT: The professor asked the students to take the quiz quickly.

("Quickly" can be moved after "to take the quiz." It is important not to create misplaced modifier by placing "quickly" at the beginning of the sentence.)

 

14. Run-on sentences

A run-on sentence is two or more independent clauses joined without the necessary punctuation separating them or the appropriate conjunction. Complex or long sentences are sometimes necessary, but you must join your ideas in a way that will not confuse the reader.

INCORRECT: It was snowing last Wednesday school was shut down.

("It was snowing last Wednesday" and "school was shut down" are both complete sentences and need the appropriate punctuation and/or conjunction to connect them.)

CORRECT: It was snowing last Wednesday, so school was shut down.

(The two complete sentences can be combined with a comma and the appropriate coordinating conjunction. A period or semicolon without the coordinating conjunction could have also fixed the run-on sentence.)

15. Fragments

A fragment is an incomplete sentence. A sentence is incomplete because it is a part of a sentence separated from an independent clause or because it is lacking a subject or predicate.

INCORRECT: GSU will have to raise tuition next year. Because the state government will not raise taxes to support education.

("Because the state government will not raise taxes to support education" does have a subject and predicate, but "because" makes this a dependent clause. It must connect to the main clause to be a complete sentence. )

CORRECT: GSU will have to raise tuition next year because the state government will not raise taxes to support education.

(The dependent clause is now a part of the main clause.)

INCORRECT: The inevitable laying off of faculty and staff.

(This sentence has no predicate. )

CORRECT: The laying off of faculty and staff is inevitable.

(The sentence is no longer a fragment because there is now a subject, "the laying off of faculty and staff," and a predicate, "is inevitable.")

 

16. Lack of subject/verb agreement

The verb in a sentence must agree with the subject in number and person. If the subject is plural, the verb form must also be plural. If singular, then singular. Additionally, if the subject is first person, the verb must be also.

INCORRECT: One of my professors always spill coffee on my papers.

(Although "professors" is plural, the subject of this sentence, "one of my professors," is singular. The plural form of the verb is wrong.)

CORRECT: One of my professors always spills coffee on my papers.

(Both the subject and verb are now singular.)

17. Vague pronoun reference

A pronoun must clearly refer to a subject. A vague pronoun reference occurs when a pronoun could refer to more than one subject or the subject that the pronoun refers to is only implied. Either way, the reader can be confused as to what subject the pronoun refers to.

INCORRECT: If your students don't do well on their quizzes, they must not be very good.

("They" is a vague pronoun in this sentence because it could refer to the students or the quizzes.)

CORRECT: Your quizzes must not be very good if your students don't do well on them.

(In this sentence, it is clear that "they" refers to the quizzes and not the students.)

18. Lack of pronoun agreement

Use pronouns exactly and consistently. The pronoun must agree with the number, gender, and type of subject.

INCORRECT: Each member of the rowing team had to set their alarm for three in the morning.

("Each member" is singular, so the pronoun must also be singular.)

CORRECT: Each member of the rowing team had to set her alarm for three in the morning.

(The noun and pronoun are both singular.)

19. Unnecessary tense shift

Use verb tenses consistently. If you start out in the present, don't shift for no reason into the past. Sometimes you need to shift tenses to reflect a change in time, but an unnecessary shift can confuse the reader as to relationship between time in what you are writing.

INCORRECT: Someone pulled the fire alarm yesterday, so we get out of class without taking the quiz.

(In this sentence there is not a clear reason to switch from the past tense, "pulled," to the present tense, "get.")

CORRECT: Someone pulled the fire alarm yesterday, so we got out of class without taking the quiz.

(Both verbs are in the past tense because there is not a clear reason to shift in time.)

20. Inappropriate passive or active voice

The active and passive voice are not grammatically correct or incorrect; however, writers often choose inappropriately which voice to use. The passive voice has the effect of removing the actor from the subject position or from the sentence entirely. This removal is appropriate in certain situations, particularly in science and business. Otherwise, you should typically use the active voice.

INCORRECT: I poured the solution into the beaker.

(The active voice would be inappropriate here if this is part of a lab report. In science writing, the person performing an experiment should be irrelevant to the process.)

CORRECT: The solution was poured into the beaker.

(Using the passive voice, the "I" can be removed from the sentence.)

INCORRECT: Native Americans were repeatedly pushed further west.

(Removing the actor from this sentence is inappropriate because it is important here to know who caused this action to occur. )

CORRECT: European settlers repeatedly pushed Native Americans further west.

(Using the active voice makes it clear who caused the action.)