Sentence Structure Study Guide for the English Basics

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Common Errors to Avoid

Even with all of this sentence structure review, it is easy to make mistakes when writing sentences, especially because the grammar with which we speak does not always align with the grammar we use in writing. Here are some common sentence writing errors to avoid.

Word Order

The word order, or syntax of your sentence is important and putting words in the wrong places can lead to a lot of confusion for your reader. Most sentences need to be organized in the following order: subject → verb → object.

It’s the place most beautiful I know.

Huh? A strange movie character might say this, but you should not write it! Instead, you would write this, to keep adjectives, adverbs, and modifiers next to the words or ideas they describe in order to create clear sentences:

It’s the most beautiful place I know.

Another, more easily made error would be:

He never had been there.

This should read:

He had never been there.

Finally, consider this:

Running I went in the rain.

Turn it into:

I went running in the rain.

Another common word order error occurs when you try to express a thought that includes a pronoun for yourself. When you are including yourself into the sentence, make sure that you select the correct personal pronoun and put the pronoun in its proper place. If in doubt about either of these, take out the other people in the sentence and see if it sounds right, like this:

Jake and me went to the movies.

If Jake doesn’t go, saying Me went to the movies makes you sound like a caveman. So the proper pronoun would be I.

Jake and I went to the movies.

But, contrary to what many believe, the use of “I” is not always correct. Try the above strategy with this sentence to uncover another very common error:

The postman delivered the package to my sister and I.

What if your sister was not at home? Would you say this?

The postman delivered the package to I.

Probably not. Instead, it should be:

The postman delivered the package to my sister and me.

This trick works with any pronoun—take the others out of the sentence and test what is left.

Her and her friends met at the mall.

What if her friends weren’t there? “Her went to the mall” is bad grammar. Replace it with she:

She and her friends went to the mall.

Double Negatives

As in math, two negatives make a positive when you are writing. Look at the following example:

I don’t need no practice before the game!

When you say it that way, it really means that you do need practice. If you needed no practice, it should only have one negative word, as do any of these choices:

I don’t need practice before the game!

I don’t need any practice before the game!

I need no practice before the game!

Here are two more examples of confusing “double negative” sentences:

You can’t see no stars out tonight.

This sentence means you must be able to see some stars because you can’t see no stars.

She never asks nobody for help.

She must be asking somebody if she’s not asking nobody.

Unnecessary Commas

Sometimes, commas just seem to find their way into sentences where they don’t belong. While commas are a common form of punctuation, here are some places they don’t need to be used:

  • Don’t allow a comma to separate a subject and its verb.
    • Incorrect: “The book on the desk, is mine.”
    • Correct: “The book on the table is mine.”
  • Only use a comma to set off a dependent clause if it starts the sentence, not if it follows an introductory independent clause.
    • Correct: “Because he doesn’t like to be bothered by people, the musician lives in a small town.”
    • Correct: “The musician lives in a small town because he doesn’t like to be bothered by people.”
    • Incorrect: “The musician lives in a small town, because he doesn’t like to be bothered by people.”
  • Do not use a comma to separate two elements joined by a coordinating conjunction.
    • Incorrect: “Joy wants to either major in chemistry, or in biology.”
    • Correct: “Joy wants to either major in chemistry or in biology.”
  • Do not use commas to set off restrictive clauses; only use them to set off information not critical to the sentence.
    • Incorrect: “The car dealership will repossess the car, unless we catch up on payments by Friday.”
    • Correct: “The car dealership, which is located in Redding, will repossess the car unless we catch up on payments by Friday.”

Comma Splices

Comma splices occur when two independent clauses are joined by only a comma. Commas are not strong enough to keep two independent clauses under control; they need help from a coordinating conjunction or to be replaced altogether by a semicolon. You can also fix a comma splice by separating the two clauses and putting each in its own sentence. Comma splices are often created when writers include transition words in the middle of a sentence. Here are some examples of comma splices and how to fix them:

Maddox didn’t review for his final exam, therefore he did not earn an A.

To fix, move the comma to after the transition word (because there should be a pause there) and use a semicolon where the comma was trying to link these two clauses together.

Maddox didn’t review for his final exam; therefore, he did not earn an A.

Incorrect: “John’s car was too small, he didn’t have room for his dog and his surfboard.”
Correct: “John’s car was too small; he didn’t have room for his dog and his surfboard.”

Incorrect: “Uncle Paul still drives his 1950 Studebaker, his trusty dog, Milo, hangs his head out the window.”
Correct: “Uncle Paul still drives his 1950 Studebaker. His trusty dog, Milo, hangs his head out the window.”

Misplaced or Dangling Modifiers

Modifiers are words, phrases, or clauses that modify or provide more information about something in the sentence. Ideally, modifiers should be placed right next to the word or idea they are describing or modifying. When the modifier is placed too far away from the word or idea it is modifying, confusion can occur. Here are some examples of misplaced modifiers and how to fix them:

“While playing in the park, Lindsey found a dirty boy’s baseball.” Hmmm… a dirty boy? That doesn’t seem like a nice description. Maybe because it’s not intended to modify the boy.

This is better:

While playing in the park, Lindsey found a boy’s dirty baseball.

Try this one:

The driver wore a uniform to drive the bus that was covered in pink polka dots.

It was a polka-dotted bus? That doesn’t seem right. Instead, write:

The driver wore a uniform covered in pink polka dots to drive the bus.

And another:

Walking down the path, the cabin came into view.

Who or what is doing the walking as the cabin came into view? That bit of information is missing, so this is a dangling modifier because it is modifying someone or something not present in the sentence. To fix, include the word or idea being modified:

As the campers were walking down the path, the cabin came into view.


Hungry, the entire pizza was eaten in less than 5 minutes.

By whom? It’s another dangling modifier and more information must be provided in the sentence.

She was so hungry that she ate the entire pizza in less than 5 minutes.

Incorrect Colon Use

A colon (:) is used:

  • for emphasis
    • “After only 30 minutes of deliberation, the jury returned with a verdict: guilty on all counts.”
  • at the end of a complete sentence to indicate the beginning of a list
    • “Humans need three things to survive: food, water, and shelter.”
  • in between independent clauses when the second explains the first
    • “Never forget this advice: do unto others as you would have done unto you.”

A colon is not a commonly used punctuation mark and should not be mistaken for a semicolon (;).

Parallel Verbs

“Parallel verbs” (also called parallelism or parallel structure) just means that all the verbs are conjugated in the same way, usually as -ing verbs (gerunds) or as infinitive verbs (to something). Here are some examples of sentences written using parallel verbs:

When Ivan goes on vacation, he likes to lie on the beach, play in the waves, and visit local sights.

Samantha said the committee was in charge of organizing the event, inviting the guests, and providing the food.

Tomorrow I will plan my trip, make reservations, and pack my bags.

Can you find the error in this sentence?

Tomorrow I will plan my trip, make reservations, and be packing my bags.

(No parallelism as a result of using be packing instead of just pack.)

Subject-Verb Agreement

Subject and verbs must match in number and tense. This means that if the sentence has a singular subject, it must have a singular verb. If there is a plural subject, it must have a plural verb (that doesn’t mean more than one verb or a verb with an s, but rather conjugating the verb to the correct plural form).

Matching tense just means ensuring that the correct form of the verb is selected based on the timeframe that the subject did it and that it is conjugated correctly. Here are some examples of subject-verb agreement errors and how to fix them:

He run 6 miles every day.

This sentence has a singular subject, he, but the verb run is in the plural form, even though it does not end with s. (“They run around the playground”).

The verb must be changed to agree with the subject.

He runs 6 miles every day.

Now we have a singular subject and a singular verb. Consider this sentence:

Dad’s glasses is on the table.

This subject is plural: glasses, so the verb must be plural.

Dad’s glasses are on the table.

The exception would be if you modified glasses with a pair: that makes it a singular subject and would require a singular verb.


“Dad’s pair of glasses is on the table; Mom’s pair is on the counter.”

And there is this:

Sasha and her friends goes swimming.

Because it’s more than one person (Sasha and her friends), this is a plural subject and needs a plural noun. This would be correct:

Sasha and her friends go swimming.

She be sitting on the beach at sunset.

This is not the right tense conjugation of the verb to be. To fix, simply replace be with the correct form:

She will be sitting on the beach at sunset.

Or, if it’s where she sat last night,

She was sitting on the beach at sunset.

And, if she’s there now,

She is sitting on the beach at sunset.

Sentences that do not have subject-verb agreement are confusing for the readers as they may not be able to identify who is doing what in the sentence if the subjects and verbs don’t match up.

Pronoun-Antecedent Agreement

An antecedent is the word that a pronoun is replacing. They must agree in number and gender to avoid confusion. For example:

Both Meg and Mark will take their SATs this weekend.

Meg and Mark is being replaced by their, which is the correct choice because the pronoun is referring to both of them.

Neither Laura nor Lydia will wear her shoes in the performance.

Although two names are listed, the neither indicates that each one is acting independently. Therefore, a plural pronoun like their won’t work and it must be her.

Every student wants to impress his or her teacher.

Again, acting as individuals, every requires a singular pronoun and since we don’t know the gender of the students, we include both his and her.

Vague Pronoun Reference

Pronouns replace nouns in a sentence. However, it is important to use them in such a way that it is clear what noun they refer to. For example:

When Jillian adopted the kitten, she was so happy.

The question is, who was happy—Jillian or the kitten? This is a vague pronoun reference. To fix, make sure the sentence is structured in such a way that the pronoun clearly matches a particular antecedent.

Jillian was so happy when she adopted the kitten.

Missing Commas

Just as it is important to not overuse commas, it is important to use them when they are needed. Remember that commas not only separate items in a list, but should also be used to separate conjunctive adverbs (adverbs or adverb phrases that indicate the relationship between independent clauses) from the rest of the sentence, if those adverbs come at the beginning of a sentence, as one does here:

Besides being hungry, Lacy was tired.

They can also come in the middle of a sentence, like this one:

Lacy took a nap; meanwhile, her mom made her a snack.

Commas (and a conjunction) must also be used when joining together two independent clauses, like this:

Lacy was tired, and she was hungry.

Split Infinitives

An infinitive is a verb form that can be used as a noun, adjective, or adverb. It usually consists of the word “to” and the simple form of a verb. Some examples of infinitives include to run, to bike, to eat, to sleep, to jump, to cry… you get the idea. A general rule of thumb, though not an actual hard-and-fast grammatical rule, is to not split the infinitive. This means don’t put another word in between the to and the verb. Here is an example of a split infinitive:

He tried to quickly hide his cell phone before his mom caught him using it at the dinner table.

In this sentence, an adverb (quickly) has been inserted between the to and hide, thereby “splitting the infinitive.” Better ways to write the sentence would be:

He quickly tried to hide his cell phone before his mom caught him using it at the dinner table.

He tried to hide his cell phone quickly before his mom caught him using it at the dinner table.

In these two revisions, the infinitive remains intact.

Sentence Sprawl

Sprawling sentences are not necessarily grammatically incorrect, but you should be mindful of your sentence length. When too many equally weighted or equally important phrases or clauses are used in one sentence, even if they are linked together correctly, the sentence can seem long or become confusing.

Write with a focus on creating sentences that are always clear and concise. Consider how you can reorder ideas or restructure the sentence to give it more clarity. One good first step is to be sure you only use the word “and” once in a single sentence. Otherwise, sentences tend to go on forever. You may be able to find other words that are used too often and signal that a sentence needs to be divided into two or more separate sentences.

Apostrophe Errors

Apostrophes serve two purposes: to form a contraction and to show possession. That’s all. Apostrophes are not used to make plurals, as in cat’s. It should only be cats. The only exception is in the case of forming the plural of a lowercase letter when the addition of only an s might confuse the meaning. You’ll need to write “The boy had trouble writing a’s” because leaving out the apostrophe would change the meaning: “The boy had trouble writing as.


A contraction is the combining of two words into one and the apostrophe serves as the placeholder for the missing letter or letters. For example:

Sara can’t have dessert tonight because she didn’t finish her dinner.

The word can’t is a combination of can and not, and the apostrophe takes the place of the letters n and o. The word didn’t is a combination of did and not, and the apostrophe holds the place of the missing o.


Apostrophes can also indicate possession—that something belongs to someone. For example:

Jaime’s bike has a flat tire.

In this sentence, we know the bike belongs to Jaime. The exception to the apostrophe-to-show-possession rule is when the pronoun it is used. To show possession using it, just add an s.

Be careful sitting on that chair because one of its legs is wobbly.

In this sentence, its is referring to the chair and the chair’s leg. The only time its will have an apostrophe is to show a contraction, such as in this one, where it’s stands for it is:

It’s snowing outside!

Wrong Words

Using the wrong words in a sentence can confuse your reader and will lessen your credibility as a writer. Make sure to review some of the most commonly misused or confused words, including: affect/effect, lay/lie, cause/because, and can/may.

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