Harper's Bazaar

Writers across magazines, offices, classrooms, and social feeds repeat the same six slips: subject-verb mismatch, misplaced apostrophes, your/you're, their/there/they're, comma overuse, and wrong punctuation placement. Run a few quick checks-identify the grammatical subject, expand contractions, test pronouns, and read aloud-to fix most problems fast.

Quick answer: six checks to run on any sentence

Check subject-verb agreement, apostrophes (possession vs. contractions), your/you're, their/there/they're, comma misuse, and punctuation placement.

Subject-verb: match the verb to the grammatical subject, not a nearby noun.
Apostrophes: possession or contraction only-never for plurals.
Your vs you're: expand to "you are"; their/there/they're: map to possessive/place/contraction.
Commas: don't split subject and verb; use commas for nonrestrictive clauses.
Punctuation: commas and periods change meaning; read aloud to check rhythm.

Core explanation: the root causes

Most errors come from writing by ear or rushing. Speakers rely on nearby words, not grammatical structure. Slow down long sentences: remove modifiers or expand contractions to reveal the true subject and meaning.

Find the grammatical subject, then pick the verb.
Expand contractions (you're → you are) to test sense.
When unsure, rewrite simply: clarity beats cleverness.

Wrong: The quality of the pieces are excellent.
Right: The quality of the pieces is excellent.

Subject-verb agreement

Identify the subject (not nouns inside prepositional phrases) and make the verb agree. Treat collective nouns as singular in American English unless context points to individuals.

Drop intervening phrases: "The list of problems is long" (ignore "of problems").
With "there is/are", invert to find the subject: "There are two options" → subject = two options.
Indefinite pronouns (everyone, nobody) take singular verbs.

Wrong: The list of contributors are on the website.
Right: The list of contributors is on the website.
Work - Wrong: The committee have sent their recommendations.
Work - Right: The committee has sent its recommendations.
School - Wrong: Each student must submit their essay by Friday.
School - Right: Each student must submit his or her essay by Friday.
Casual - Wrong: There is two more episodes to watch.
Casual - Right: There are two more episodes to watch.

Apostrophes: possession and contractions, not plurals

Apostrophes mark possession (the editor's note) or contractions (it's = it is). They do not form plurals.

Plural nouns: add s or es (apples, editors). No apostrophe.
Singular possessive: add 's (the writer's desk). Plural possessive: writers' lounge.
If unsure, rewrite: "the notes of the editor" avoids apostrophe confusion.

Wrong: I found three editor's suggestions on the doc.
Right: I found three editors' suggestions on the doc.
Casual - Wrong: Its been a long week.
Casual - Right: It's been a long week.
School - Wrong: The students' assignment was late (referring to one student).
School - Right: The student's assignment was late.

Your / You're and Their / There / They're

Use substitution tests: replace you're with "you are"; replace they're with "they are." For their/there, decide possession vs. place.

"You're" → expand to "you are" to check correctness.
"Their" = ownership; "there" = place or expletive subject; "they're" = "they are."
Run a quick find for these words in long drafts and check each instance manually.

Casual - Wrong: Your going to love the issue on fall trends.
Casual - Right: You're going to love the issue on fall trends.
School - Wrong: There books are on the desk.
School - Right: Their books are on the desk.
Work - Wrong: Theyre final edits will go live tomorrow.
Work - Right: They're final edits will go live tomorrow.
Casual - Wrong: I left my coat over their.
Casual - Right: I left my coat over there.

Commas and punctuation placement

Commas separate items, set off nonessential clauses, and mark natural pauses. Avoid commas that split subject and verb or create fragments.

Don't separate subject and verb with a comma unless a clause requires it.
Use commas for nonrestrictive clauses-remove the clause; if meaning stays, keep the commas.
Punctuation around quotes and parentheses follows house style; read aloud to check flow.

Casual - Wrong: Let's eat grandma.
Casual - Right: Let's eat, grandma.
Work - Wrong: The report, which you wrote is on my desk.
Work - Right: The report, which you wrote, is on my desk.
School - Wrong: The dog, barked, loudly, at the mailman.
School - Right: The dog barked loudly at the mailman.
Casual - Wrong: After dinner we, went to the show.
Casual - Right: After dinner, we went to the show.

Try your own sentence

Test the whole sentence in context. If a single phrase still feels wrong, read the sentence aloud or substitute a noun for ambiguous pronouns.

Fix your sentence: three-step rewrite method + examples

Three steps: 1) Underline the main subject and verb. 2) Expand contractions and replace vague pronouns with nouns. 3) Tweak commas and shorten the sentence if it still trips you.

Step 1: Find the grammatical subject-this reveals the correct verb form.
Step 2: Replace they're/your/its with they are/you are/it is to test sense.
Step 3: Simplify if you stumble when reading the sentence aloud.

Rewrite: Original (work): The board, including the new members, are meeting tomorrow. →
Rewrite: The board, including the new members, is meeting tomorrow.
Rewrite: Original (school): Each of the students have turned in their surveys. →
Rewrite: Each of the students has turned in his or her survey. Or: All students have turned in their surveys.
Rewrite: Original (casual): Your going to love this look, its so you. →
Rewrite: You're going to love this look; it's so you.
Rewrite: Original (work): The freelance writers deadline was extended. →
Rewrite: The freelance writer's deadline was extended. (or: The freelance writers' deadline was extended.)

Real usage and tone: editorial vs casual

Voice affects tolerance for contractions and fragments, but clarity is nonnegotiable. Social captions can be looser; features and academic copy should be precise.

Casual: contractions and short fragments are fine if meaning is clear.
Editorial/features: preserve rhythm and voice, but avoid sloppy agreement and misplaced apostrophes.
Academic: avoid ambiguous pronouns; prefer explicit phrasing or pluralization.

Casual - Usage: You're going to love this look. (contraction acceptable)
Work - Usage: The editor's note explains the fall issue's theme in full detail. (formal possession)
School - Usage: Each participant must submit a survey before the deadline. (avoids gendered pronouns)

Memory tricks, hyphenation, and spacing

Keep tiny rules handy: "you're = you are"; "its" (possessive) vs "it's" (it is). Hyphenate compound modifiers before nouns. Use a single space after periods in online text.

Mnemonic for their/there/they're: "their stuff" (possession), "over there" (place), "they're = they are" (contraction).
Hyphenate: well-known author, award-winning piece. Do not hyphenate adverb + participle with -ly (highly regarded).
Spacing: one space after a period for web text; remove double spaces and extra spaces before punctuation.

Work - Usage: Wrong: a well known actress →
Right: a well-known actress
Casual - Usage: Wrong: She walked 5 km's every day. →
Right: She walked 5 km every day.
Work - Usage: Wrong: The award winning piece was praised. →
Right: The award-winning piece was praised.

Similar mistakes and final pre-publish checklist

Before publishing, run this short list on every paragraph or paste your text into a checker and apply these manual checks.

Checklist: subject-verb agreement; your/you're and their/there/they're; apostrophes; comma placement; hyphenation; single spaces and no stray spaces before punctuation.
Check quotation punctuation per house style and keep heading capitalization consistent.
If a sentence keeps failing checks, rewrite it shorter and test again.

Wrong: She said, 'The dress is mine' .
Right: She said, 'The dress is mine.'
School - Wrong: The well known critic, praised the show.
School - Right: The well-known critic praised the show.

FAQ

How do I know when to use its vs it's?

Replace it's with "it is" or "it has." If the sentence still makes sense, use it's. If you mean possession, use its without an apostrophe.

Is "team" singular or plural?

In American English, "team" is usually singular: The team is winning. If you mean the individuals, say "team members are" or follow a style guide that allows plural collective nouns.

Should I use a comma before "and" in a list?

The Oxford comma is a style choice. Use it for clarity ("bread, cheese, and wine") or follow your house style consistently.

How can I quickly fix a sentence I suspect is wrong?

Underline the subject and verb, expand contractions, swap ambiguous pronouns for nouns, remove nonessential phrases, and read aloud. If it still trips you, rewrite shorter.

What's the best way to catch repeated mistakes across an article?

Run targeted finds (your, their, it's, its), apply substitution tests, keep a short checklist, and review automated suggestions manually for tone and accuracy.

Want to check one sentence now?

Paste a single sentence into a grammar tool or run the three-step test above. Short, direct sentences are easier to proof and less likely to contain these recurring mistakes.