4.2 Common Sentence Errors


This section of Ch. 4 will cover the following topics:

  • subject-verb agreement
  • misplaced and dangling modifiers
  • parallel structure

Writing mistakes make a negative impression on a reader (and on a grade). Three common sentence errors are subject-verb agreement, modifier problems, and lack of parallel structure. By understanding parts of speech and sentence structure, these three errors can be avoided.

Subject-Verb Agreement

“Subject-verb agreement” means the of a sentence and the of a sentence must agree with each other in number. A singular subject belongs with a singular verb, and a plural subject belongs with a plural verb. For example:

Singular: The cat jumps over the fence.
Plural: The cats jump over the fence.

Errors in subject-verb agreement are common, especially when the subject of the sentence is separated from the verb by other words.

If you have trouble finding the subject and verb in a sentence, cross out the prepositional phrases and dependent clauses. The subject of a sentence will never be in a prepositional phrase or dependent clause.

For example, the prepositional phrases that separate the subject and verb have been crossed out here:

The students with the best grades win the academic awards.
The puppy under the table is my favorite.

Removing the prepositional phrases makes it easy to identify the subjects (“students,” “puppy”) and the verbs (“win,” “is”).

Dependent clauses that separate the subject and verb have been crossed out here:

The car that I bought has power steering and a sunroof.
The representatives who are courteous sell the most tickets.

That makes it easier to see the subjects (“car,” “representatives”) and the verbs (“has,” “sell”). And it makes it very easy to see that the subjects and verbs agree in number.

Exercise 1

Type the sentences below, correcting any errors in subject-verb agreement.  Start by crossing out prepositional phrases and dependent clauses so you can easily find the subject and the verb.

  1. My sister and brother fights during every meal.
  2. The books in the college library is easy to locate.
  3. Our renters cleans up after themselves.
  4. Some of the holiday decorations is packed away in the attic.
  5. Squirrels in my attic and basement annoys me.


A modifier is a word, phrase, or clause that clarifies or describes another word, phrase, or clause. Adjectives and adverbs are modifiers. Phrases and clauses can also work as modifiers. Modifiers make writing more interesting, but also more prone to errors.

Two common modifier errors are misplaced modifiers and dangling modifiers. When these errors occur, readers become confused trying to figure out what the writer meant.

A misplaced modifier is too far from the word or words it modifies. Misplaced modifiers make a sentence awkward and sometimes unintentionally funny. For example:

She wore a bicycle helmet on her head that was too large.

This seems to say her head was too large. The modifying phrase “that was too large” should be closer to the word “helmet.” The modifier is misplaced.

Corrected: She wore a bicycle helmet that was too large on her head.

Here is another example:

The patient was referred to a physician with stomach pains. (Does the doctor have stomach pains? The modifier “with stomach pains” is too far from the word “patient.”)

Corrected: The patient with stomach pains was referred to a physician.

A dangling modifier is a word, phrase, or clause that describes something that isn’t in the sentence. When there is nothing the word, phrase, or clause can modify, the modifier is said to “dangle.” For example:

Riding in the sports car, the world whizzed by rapidly. (Who is riding in the sports car? The modifier “riding in the sports car” is dangling.)

Corrected: When Farzad was riding in the sports car, the world whizzed by rapidly.

Here is another example:

Walking home at night, the trees looked like spooky aliens. (Who is walking? The modifier “walking home at night” is dangling.)

Corrected: As Sarah was walking home at night, the trees looked like spooky aliens.

Exercise 2

Type the following sentences, moving or adding information to correct misplaced or dangling modifiers.

  1. Chewing furiously, the gum fell out of my mouth.
  2. The young woman was walking her dog on the telephone.
  3. Piled up next to the bookshelf, I chose a mystery novel.
  4. I heard there was a fire on the evening news.
  5. We are looking for a sitter for our baby who doesn’t smoke and owns a car.
  6. The teacher served snacks to the children wrapped in aluminum foil.
  7. Lily spotted a stray dog driving home from work.
  8. While driving to the veterinarian’s office, the dog nervously whined.

Parallel Structure

When something is parallel to something else, they are similar in form. For example, two parallel lines look like this:


Parallelism in writing is the use of a similar structure in related words, clauses, or phrases. For example, these three phrases have parallel structure:

in the pool, in the forest, in the book

They feel balanced. Also, they are easy to read and remember.

Now look at these word groups:

in the pool, forests are green, book shelf

They are different from each other in structure. Notice how jagged it feels to read them, and they are more difficult to remember.

Parallel structure creates rhythm and balance within a sentence. An unbalanced sentence sounds awkward. Read the following sentences aloud:

Kelly had to iron, do the washing, and shopping before her parents arrived.

Driving a car requires coordination, patience, and to have good eyesight.

Swimming in the ocean is much tougher than a pool.

All of these sentences contain faulty parallelism. The construction is clunky and confusing. In the first example, three different verb forms are used (“had to iron,” “do the washing,” “shopping”). In the second example, the writer begins with nouns (“coordination,” “patience”), but ends with a phrase (“to have good eyesight”).  In the third sentence, the writer is comparing an action (“swimming”) with a thing (“a pool”).

Here are the same sentences with correct parallelism:

Kelly had to do the ironing, washing, and shopping before her parents arrived. (The verbs have the same structure.)

Driving a car requires coordination, patience, and good eyesight. (The three qualities are all written as nouns.)

Swimming in the ocean is much tougher than swimming in a pool. (One action is being compared with another action.)

When sentences use parallel structure, they sound more pleasing. Repetition of the pattern also minimizes the work a reader has to do to understand the sentence.

Exercise 3

Type up the following sentences, making any necessary changes to correct parallel structure problems.

  1. I would rather work at a second job to pay for a new car than a loan.
  2. How you look in the workplace is just as important as your behavior.
  3. Indian cuisine is tastier than the food of Great Britain.
  4. Jim’s opponent in the ring was taller, carried more weight, and not as strong.
  5. Working for a living is much harder than school.

An Example of Parallel Structure

Some of the most beautiful pieces of writing and many great historical speeches use parallel structure to emphasize important points and create a smooth, easily understandable idea.

For example, here is a paragraph from Martin Luther King, Jr.’s “I Have a Dream” speech:

But one hundred years later, the Negro still is not free. One hundred years later, the life of the Negro is still sadly crippled by the manacles of segregation and the chains of discrimination. One hundred years later, the Negro lives on a lonely island of poverty in the midst of a vast ocean of material prosperity. One hundred years later, the Negro is still languished in the corners of American society and finds himself an exile in his own land. And so we’ve come here today to dramatize a shameful condition.

Not only does King repeat the phrase “One hundred years later” to drill that fact into the listener’s memories, but he also uses more subtle parallel structure in “the manacles of segregation and the chains of discrimination.” These phrases are similar in structure (article + plural noun + preposition + noun), and the words within each part are similar in form (“manacles” and “chains,” “segregation” and “discrimination”).

Great writers and speakers are aware of the power of parallel structure to clearly communicate ideas.


  • A verb must always agree with its subject in number. A singular subject requires a singular verb; a plural subject requires a plural verb, even when the subject and verb are separated.
  • Misplaced and dangling modifiers make sentences difficult to understand.
  • Parallelism creates rhythm and balance in writing by using the same grammatical structure. Faulty parallelism makes a sentence clunky and awkward.


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