Reading & Writing

Boundaries

2 min readMedium5-question drill

Boundaries questions are pure punctuation: commas, semicolons, colons, and periods deciding where one idea stops and another begins. They show up several times per test, and once you know the rules, they're free points.

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Boundaries

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Boundaries questions test whether you can punctuate the edges between and within sentences correctly. The test won't ask you to define a semicolon — it'll give you a sentence with a blank and four punctuation options, and you pick the one that follows the rules.

The single most important idea: independent clause vs. dependent clause.

An independent clause is a complete sentence — it has a subject and a verb and can stand alone (The dog barked).
A dependent clause cannot stand alone (Because the dog barked).

Here are the core rules you'll use again and again:

Two independent clauses can be joined by:
- A period (. ) — makes two sentences.
- A semicolon (;) — works just like a period.
- A comma + FANBOYS conjunction (, and / , but / , so / , for / , or / , nor / , yet).
Comma splice = joining two independent clauses with just a comma. This is ALWAYS wrong. The dog barked, the cat ran is broken.
Colon (:) follows an independent clause and introduces a list, explanation, or example: She packed three things: a map, water, and a knife. The part before the colon must be a complete sentence.
Nonrestrictive (nonessential) elements — extra info you could delete — get set off with commas on both sides: My brother, a chef, loves knives. If you open with a comma, you must close with one too.
Don't separate a subject from its verb with a single comma. The tall man in the hat, walked away is wrong.

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Are both sides complete sentences?

Yes ↓

Is there a FANBOYS word?

Yes ↓

→ Use comma + FANBOYS

No ↓

→ Use a semicolon or period

No ↓

→ Use a comma (or no punctuation)

Quick decision chain for joining clauses.

Watch out for words like however, therefore, moreover, consequently — these are NOT FANBOYS. They cannot fix a comma splice. When however joins two complete sentences, you need a semicolon before it: Sales rose; however, profits fell.

Sales rose; however, profits fell. The team worked hard, but the deadline slipped.

conjunctive adverb - needs ;FANBOYS - needs , before

'however' takes a semicolon; 'but' takes a comma.

Your strategy on every Boundaries question: ignore the meaning, and instead check what's on each side of the blank. Is the left side a complete sentence? Is the right side? That answer tells you which punctuation is legal.

The novelist's debut book, which she wrote in six months,became a bestseller.

Nonrestrictive (extra info)

A nonessential clause fenced by commas on both sides.

Quick check

Check your understanding with a question from this topic:

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

The committee reviewed dozens of proposals_______ only three were selected for funding.

Which choice completes the text so that it conforms to the conventions of Standard English?

Example 2

The novelist's debut book_______ which she wrote in just six months_______ became an international bestseller.

Which choice completes the text so that it conforms to the conventions of Standard English?

Example 3

Her research focused on three coastal ecosystems_______ mangroves, salt marshes, and coral reefs.

Which choice completes the text so that it conforms to the conventions of Standard English?

Common pitfalls

Treating 'however' like a FANBOYS conjunction

Words like however, therefore, moreover, consequently are conjunctive adverbs, not coordinating conjunctions. They cannot fix a comma splice — you need a semicolon or period before them: It rained; however, we played.

Closing a nonessential phrase with only one comma

If a clause set off by commas could be deleted, it needs commas on both sides. Test-writers love offering choices that put a comma on just one end — always check that the fences match.

Putting a colon after an incomplete clause

A colon requires a complete sentence on its left. Three ecosystems she studied: mangroves... is wrong because Three ecosystems she studied isn't a full sentence. Read everything before the colon and make sure it stands alone.

Reading for meaning instead of structure

Boundaries questions are about grammar, not content. Don't pick punctuation that 'feels' right — identify whether each side is independent or dependent, then apply the rule.

Key takeaways

Two independent clauses join with a period, a semicolon, or a comma + FANBOYS — never a comma alone.
Nonessential (deletable) phrases must be enclosed by commas on both sides.
A colon needs a complete sentence before it and introduces a list, explanation, or example.
Conjunctive adverbs (however, therefore, moreover) need a semicolon before them, not a comma.
Solve by checking the structure of each side of the blank, not by the meaning of the sentence.

Watch & learn

Curated Khan Academy walkthroughs on Boundaries. They're complementary to this lesson — watch one if a written explanation isn't clicking, or after to reinforce.

Tracks your progress across lessons.

Try it yourself

5 practice questions on Boundaries, drawn from the question bank. The tutor is one click away if you get stuck.

Where this lesson fits

Boundaries

You are here

→Transitions →Form, Structure, and Sense