Comma questions show up on nearly every test, and they're some of the most reliable points you can grab — once you know the four jobs a comma actually does, you stop guessing and start knowing.
A nonessential clause is set off by commas on both sides.
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Are both sides complete sentences?
Yes ↓
Is there a FANBOYS word (and, but, so...)?
Yes ↓
→ Use comma + FANBOYS
No ↓
→ Use a semicolon
No ↓
→ A comma alone may be fine — no semicolon
Deciding between comma and semicolon for joining clauses.
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The artist who painted this mural is famous; however, few people know her name.
essential — no commassemicolon joins clauses
Essential clause takes no commas; 'however' takes a semicolon.
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Quick check
The artist's latest exhibition features landscapes painted in a style reminiscent of the Impressionists_______ however, her use of digital tools gives the works a distinctly contemporary feel.
Which choice completes the text so that it conforms to the conventions of Standard English?
Worked examples
Example 1
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Example 2
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Example 3
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Common pitfalls
Comma splice with however/therefore
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Forgetting the second nonessential comma
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Splitting subject and verb
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Using a comma where info is essential
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Key takeaways
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Tracks your progress across lessons.
Try it yourself
5 practice questions on Comma Rules, drawn from the question bank. The tutor is one click away if you get stuck.
A comma's job is to separate parts of a sentence so the meaning stays clear. The test cares about a handful of specific situations. Master these and you'll handle almost every comma question.
First, some vocabulary. An independent clause is a group of words that could stand alone as a complete sentence — it has a subject and a verb and expresses a full thought (The dog barked). A dependent clause can't stand alone (Because the dog barked).
Here are the main comma rules the test checks:
1. Items in a list. Separate three or more items with commas: apples, oranges, and pears. The comma before and is fine and expected.
2. Setting off nonessential information. A nonrestrictive (nonessential) element is extra info you could delete and still have a complete, sensible sentence. Set it off with commas on both sides: Maria, who studies coral, won the prize. If the info is essential (you need it to know who/what is meant), use NO commas.
3. Joining clauses. To join two independent clauses you need either a comma + a FANBOYS conjunction (for, and, nor, but, or, yet, so) OR a semicolon. A comma alone between two independent clauses is a comma splice — always wrong.
4. After an introductory element. Put a comma after an opening phrase or dependent clause: After the storm, we cleaned up.
The test also loves to make you NOT use a comma. A frequent trap: never put a single comma between a subject and its verb.The artist who painted this[comma] is famous is wrong — that lone comma splits the subject from the verb.
A strategy that works almost every time: read the choices and ask what is this comma (or semicolon) connecting? Identify whether each side is a complete sentence, whether the middle chunk is removable, and whether you're looking at a list. The punctuation follows from the structure — you don't have to 'hear' it.
The museum's collection includes works by several renowned artists_______ Frida Kahlo, Georgia O'Keeffe, and Yayoi Kusama.
Which choice completes the text so that it conforms to the conventions of Standard English?
Maria, who had been studying marine biology for over a decade_______ was the first to identify the new species of coral.
Which choice completes the text so that it conforms to the conventions of Standard English?
The artist's latest exhibition features landscapes painted in a style reminiscent of the Impressionists_______ however, her use of digital tools gives the works a distinctly contemporary feel.
Which choice completes the text so that it conforms to the conventions of Standard English?
Words like however, therefore, and moreover are NOT conjunctions. Joining two independent clauses with a comma + 'however' is a comma splice. Use a semicolon before them instead.
If a nonrestrictive phrase opens with a comma, it must close with one too. Test makers often give you the opening comma and bait you into skipping the closing one.
A single comma should never sit between a subject and its verb. If you can't remove the chunk after the comma, the comma probably doesn't belong there.
If deleting a phrase changes which person or thing you mean, it's essential — use NO commas. 'The student who cheated was expelled' needs no commas around 'who cheated.'
A comma alone cannot join two independent clauses — use a semicolon or comma + FANBOYS.
Nonessential information gets commas on BOTH sides; essential information gets none.
Put a comma after an introductory phrase or dependent clause.
Never place a single comma between a subject and its verb.
Transition words like 'however' take a semicolon before them when joining two complete sentences.