08 English Grammar and Mechanics
Learn how sentence structure, agreement, pronouns, modifiers, punctuation, and word choice work together to make English writing clear.
Build complete sentences
A contains a subject and a verb. An expresses a complete thought, while a does not. For example, “The nurse reviewed the chart” is complete, but “After the nurse reviewed the chart” is not. The can be part of a complete sentence: “After the nurse reviewed the chart, she called the physician.”
A sentence fragment is missing a necessary part or consists only of a . For example, “Because the patient was resting” is a fragment; “The patient was not disturbed because she was resting” is complete.
A joins independent clauses without correct punctuation. A is a in which the clauses are joined with only a comma. “The clinic was busy, the staff stayed calm” is a . Correct alternatives include “The clinic was busy, but the staff stayed calm” and “The clinic was busy; the staff stayed calm.”
Join independent clauses with a period, a , or a comma plus a coordinating conjunction: for, and, nor, but, or, yet, so. A can also come before a connecting adverb such as however or therefore: “The sample was small; therefore, the results were limited.”
Check agreement and pronouns
means that a singular subject takes a singular verb and a plural subject takes a plural verb. Identify the true subject rather than being distracted by words between the subject and verb. In “The list of medications is on the counter,” list is the subject. In “The medications are on the counter,” the subject is plural. The singular subject each takes a singular verb in “Each of the applicants has an appointment.”
With either…or and neither…nor, the verb generally agrees with the nearer subject: “Either the instructor or the students are presenting.”
A pronoun should clearly refer to a noun, its , and agree with it in number. In “When the aide spoke to the nurse, she was concerned,” it is unclear whether she means the aide or the nurse. Recasting the sentence can clarify the reference: “The aide was concerned when speaking to the nurse.” Singular they is widely used for a person whose gender is unknown or who uses that pronoun; follow the wording and conventions requested by the test or context.
Choose pronoun case according to the pronoun’s role. Use subject forms (I, he, she, we, they) for subjects, and object forms (me, him, her, us, them) for objects of verbs or prepositions. For example, “Jordan and I reviewed the chart” uses a subject form, while “The supervisor spoke with Jordan and me” uses an object form. To check a compound phrase, temporarily remove the other person: “The supervisor spoke with me,” not “with I.”
Place modifiers and match forms
Place a modifier close to the word it describes. A has no clear word to describe. In “After reviewing the chart, the patient’s condition seemed stable,” the sentence makes it seem that the condition reviewed the chart. The revision “After reviewing the chart, the nurse judged the patient’s condition stable” makes the intended relationship clear.
Items joined in a list or comparison should use , meaning they have matching grammatical forms. “The role requires observing carefully, patience, and to communicate clearly” is not parallel. “The role requires careful observation, patience, and clear communication” uses matching forms.
Use commas to show relationships
Use commas to separate items in a series, after most introductory dependent clauses, and around nonessential information. Use a comma before a coordinating conjunction when it joins two independent clauses. Do not put a comma between a subject and its verb.
Introductory : “Before the exam began, the students checked their supplies.”
Nonessential information: “The student, who had arrived early, reviewed her notes.” The adds extra information.
Identifying information: “The student who had arrived early found a seat.” The identifies which student, so it is not set off with commas.
Incorrect subject–verb separation: “The results of the second test, were clear.”
A comma alone cannot join two complete sentences.
Use semicolons, colons, and apostrophes
Use a between closely related independent clauses, or between list items that already contain commas. For example: “The test was repeated; the second result was consistent.”
Use a after a complete to introduce an explanation or list: “Bring three items: identification, a pencil, and water.” Do not place a where the words before it do not form a complete . “Bring: identification, a pencil, and water” is incorrect.
Use apostrophes for possession and contractions, not for ordinary plurals. “The nurse’s notes” refers to one nurse; “the nurses’ notes” refers to multiple nurses. Similarly, use “the patient’s chart” for one patient and “the patients’ charts” for multiple patients. It’s means it is or it has; its means belonging to it. “The report’s conclusion” is possessive, but “three reports” is a plural with no apostrophe.
In standard American punctuation, commas and periods usually go inside closing quotation marks: “The note said, ‘Call the clinic.’”
Choose commonly confused words
Choose the word that fits both the sentence’s meaning and its grammar. These distinctions are common proofreading targets, so read for meaning rather than relying on sound alone.
your / you’re: your means belonging to you; you’re means you are. “You’re responsible for your supplies.”
their / there / they’re: their means belonging to them; there refers to a place; they’re means they are. “They’re leaving their bags there.”
its / it’s: its means belonging to it; it’s means it is or it has. “It’s clear that the device lost its charge.”
affect / effect: affect is usually a verb meaning influence; effect is usually a noun meaning result. “Sleep can affect attention; its effect may be significant.”
than / then: than is used in comparisons; then refers to time or sequence. “The second reading was higher than the first; then we recorded it.”
to / too / two: to indicates direction or forms an infinitive; too means also or excessively; two is the number. “The two students went to the lab, too.”
who / whom: who is used as a subject; whom is used as an object. “Who called? To whom did you speak?”
Proofread in a consistent order
Edit in an order that checks sentence meaning and structure before smaller details:
Find each sentence’s subject and verb, then check agreement.
Confirm that each sentence expresses a complete thought.
Check how independent clauses are joined.
Verify pronoun reference, modifier placement, and parallel wording.
Review commas, apostrophes, and commonly confused words.
Clear sentences have complete structures, matching subjects and verbs, and pronouns with clear references. Correct punctuation shows how clauses and ideas relate, while precise word choice preserves meaning.