Key Takeaways

  • Commas separate items in a list, after introductory elements, before conjunctions in compound sentences, and around non-essential clauses
  • Semicolons connect two closely related independent clauses without a conjunction
  • Colons introduce lists, explanations, or elaborations after an independent clause
  • Apostrophes show possession (nurse's) or contraction (don't); they are never used to form plurals
  • A sentence fragment lacks a subject, verb, or complete thought; a run-on sentence joins independent clauses without proper punctuation
  • Independent clauses contain a subject and verb and express a complete thought; dependent clauses cannot stand alone
  • Parallel structure requires that items in a series use the same grammatical form
  • Misplaced and dangling modifiers create confusion by not clearly connecting to the word they modify
Last updated: February 2026

Punctuation & Sentence Structure

Proper punctuation ensures clarity in written communication. In nursing, a misplaced comma or an ambiguous sentence can lead to errors in patient care.


Comma Rules

RuleExample
Items in a series"Check the patient's pulse, blood pressure, and temperature."
After introductory elements"Before administering the medication, verify the patient's identity."
Before a conjunction in a compound sentence"The patient was alert, but she was in moderate pain."
Around non-essential (parenthetical) information"Dr. Smith, the chief surgeon, performed the operation."
Between coordinate adjectives"The patient had a high, persistent fever."
After transitional words"However, the test results were inconclusive."

Common Comma Errors:

  • Comma splice: Joining two independent clauses with only a comma (incorrect)
    • Wrong: "The patient was stable, she was discharged."
    • Right: "The patient was stable, so she was discharged."
    • Right: "The patient was stable; she was discharged."

Semicolons

Semicolons have two main uses:

  1. Connect two closely related independent clauses (without a conjunction):

    • "The patient's fever broke; his vital signs returned to normal."
  2. Separate items in a list when the items contain commas:

    • "The conference attendees came from Houston, Texas; Portland, Oregon; and Miami, Florida."

Colons

Use a colon after an independent clause to introduce:

  • A list: "The nurse checked three things: pulse, respiration, and blood pressure."
  • An explanation: "There was one problem: the patient was allergic to penicillin."
  • A quotation: "The doctor stated: 'The patient needs immediate surgery.'"

Rule: The clause before the colon must be a complete sentence.


Apostrophes

UseRuleExample
Possession (singular)Add 's"the nurse's station"
Possession (plural ending in s)Add '"the nurses' lounge"
Possession (plural not ending in s)Add 's"the children's ward"
ContractionsReplace omitted letters"don't" (do not), "it's" (it is)
NOT for pluralsNever use to make a word plural"The nurses are here" (NOT "nurse's")

Common Confusion:

  • it's = it is ("It's important to wash hands")
  • its = possessive ("The hospital updated its policy")
  • your = possessive ("Your shift starts at 7 AM")
  • you're = you are ("You're responsible for this patient")

Additional Commonly Confused Words in Healthcare

PairDefinitionsCorrect Usage
than / thenthan = comparison; then = time/sequence"The patient's BP is higher than yesterday." / "Check the pulse, then document it."
accept / exceptaccept = to receive; except = to exclude"The ER will accept the transfer." / "All labs are normal except potassium."
who's / whosewho's = who is; whose = possessive"Who's the attending physician?" / "Whose chart is this?"
there / their / they'rethere = place; their = possessive; they're = they are"The supplies are over there." / "Their vitals are stable." / "They're ready for discharge."
compliment / complementcompliment = praise; complement = to complete"She received a compliment on her care." / "The medications complement each other."
principle / principalprinciple = rule/belief; principal = main/chief"The principle of non-maleficence." / "The principal concern is infection."
stationary / stationerystationary = not moving; stationery = writing materials"The patient remained stationary." / "Order new stationery for the nurses' station."
conscious / conscienceconscious = awake/aware; conscience = moral sense"The patient is conscious and alert." / "Follow your conscience in ethical dilemmas."

Sentence Structure

Types of Sentences

TypeStructureExample
SimpleOne independent clause"The nurse administered the medication."
CompoundTwo independent clauses joined by a conjunction or semicolon"The nurse assessed the patient, and she documented the findings."
ComplexOne independent + one dependent clause"Although the patient was stable, the nurse continued monitoring."
Compound-ComplexTwo independent + one dependent clause"When the alarm sounded, the nurse rushed to the room, and the doctor followed."

Common Sentence Errors

1. Sentence Fragment: Missing a subject, verb, or complete thought.

  • Fragment: "Running down the hallway to the emergency room."
  • Correct: "The nurse was running down the hallway to the emergency room."

2. Run-on Sentence: Two independent clauses joined without proper punctuation.

  • Run-on: "The patient was stable she was discharged the next morning."
  • Correct: "The patient was stable, and she was discharged the next morning."

3. Parallel Structure: Items in a series must use the same grammatical form.

  • Incorrect: "The nurse enjoys assessing patients, to educate families, and documentation."
  • Correct: "The nurse enjoys assessing patients, educating families, and documenting care."

4. Misplaced Modifier: A modifier placed too far from the word it describes.

  • Misplaced: "The nurse treated the patient wearing sterile gloves." (Who wore gloves?)
  • Correct: "Wearing sterile gloves, the nurse treated the patient."

5. Dangling Modifier: A modifier with no clear subject.

  • Dangling: "After reviewing the chart, the medication was administered."
  • Correct: "After reviewing the chart, the nurse administered the medication."

Clauses and Phrases

Understanding the difference between clauses and phrases is essential for sentence analysis:

Clause = a group of words with a subject AND a verb

  • Independent clause — can stand alone as a sentence: "The patient was stable."
  • Dependent clause — cannot stand alone; begins with a subordinating conjunction: "Although the patient was stable..." (needs more to complete the thought)

Common subordinating conjunctions: although, because, since, if, when, while, after, before, until, unless, even though

Phrase = a group of words WITHOUT a subject-verb combination

  • Prepositional phrase: "in the hospital," "after the surgery," "under the bed"
  • Participial phrase: "Running quickly, the nurse reached the patient."
  • Infinitive phrase: "to administer the medication"

Direct and Indirect Objects

ElementDefinitionExample
SubjectWho/what performs the action"The nurse gave the patient medication."
VerbThe action"The nurse gave the patient medication."
Direct objectWhat receives the action directly"The nurse gave the patient medication."
Indirect objectWho/what receives the direct object"The nurse gave the patient medication."

Tip: To find the direct object, ask "What?" after the verb. To find the indirect object, ask "To whom?" or "For whom?"

HESI A2 Grammar Section — Approximate Topic Distribution (%)
Test Your Knowledge

Which sentence is punctuated correctly?

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Test Your Knowledge

Which sentence contains a dangling modifier?

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Test Your Knowledge

Select the sentence with correct parallel structure.

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Test Your Knowledge

Choose the correct use of the apostrophe.

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Test Your KnowledgeFill in the Blank

A sentence that joins two independent clauses with only a comma (no conjunction) is called a comma _____.

Type your answer below

Test Your Knowledge

Which word correctly completes this sentence: "_____ important to follow the medication schedule."

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Test Your Knowledge

Identify the sentence fragment.

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