SAT semicolons, colons, and dashes

What the question looks like

The question always reads: “Which choice completes the text so that it conforms to the conventions of Standard English?” It never names the mark, so look at the choices. They keep the same words and change the punctuation, and sometimes a capital letter or a small added word changes too.

Check each side of the blank

Run the check on this blank:

“The flood left one thing behind ______ a layer of gray silt.”

Look back toward the start of the sentence. If a , dash, or parenthesis opened some extra words, the blank may close them with the same mark. Nothing opens here.
Read the words before the blank as if the sentence stopped there: “The flood left one thing behind.” That could stand alone.
Read the words after the blank as if a new sentence started there: “A layer of gray silt.” That can’t, because it has no .
Match what you found:
- If both sides could, use a period or a semicolon, or a comma plus “and,” “but,” or “so.” A comma alone is wrong, and so is no mark. A colon or one dash also works when the second sentence explains the first.
- If the left side could and the right side explains or lists, use a colon or one dash.
- If the left side could and the right side is extra words that describe or comment on it, use a comma, as in “The flood left silt behind, which enriched the fields.”
- If the left side is only opening words, use a comma.
- If the blank splits words that belong together, such as a and its verb, use no mark.
- If the blank sits between list items that already contain commas, use a semicolon.

Here only the left side could stand alone, and the right side names the one thing, so the blank takes a colon or a dash.

When step 1 does find an opening mark, that mark decides the blank. In “The flood—the worst in forty years ______ left a layer of gray silt,” a dash opened extra words after “flood,” so the blank closes them with a second dash.

A side can stand alone when it has a subject and a verb with a time on it, such as “cooled,” and no waiting word such as “because” or “which” holding it open. Sentence boundaries teaches that test in full.

Don’t go by the pause you hear when you read the sentence aloud. A comma, a semicolon, a colon, and a dash can all sound alike, and each one allows different words around it.

A semicolon between full sentences

A semicolon needs a full sentence on each side.

Right: The chamber cooled; the pressure fell.
Wrong: The chamber cooled; although the pressure fell.

'Although' leaves you waiting, so 'although the pressure fell' can’t stand alone.

Trap: One added word

“The chamber cooled; which lowered the pressure.” Next to a choice like “cooled; this lowered,” it looks almost the same. “This lowered the pressure” could stand alone, but “which lowered the pressure” points back to the first half and leaves you waiting.

What to do: Read the right side alone with the choice’s words in place. If it starts with a waiting word, the semicolon is wrong.

Semicolons with however and therefore

“However,” “therefore,” “consequently,” and “nevertheless” link two ideas, but they can’t join two full sentences the way “and” can. To pick the marks around one of them, cover the word and read what’s left.

When “therefore” starts the second full sentence, put a semicolon before it and a comma after it.

Right: The roof leaked; therefore, the records became damp.
Wrong: The roof leaked, therefore, the records became damp.

Cover 'therefore' and two full sentences are left with only a comma between them.

When “however” sits inside one sentence, put a comma on each side of it.

Right: The records, however, survived.
Wrong: The records; however; survived.

Cover 'however' and one sentence is left: 'The records survived.' The semicolons split the subject from its verb.

When the choices also move “however” from one sentence to the other, Sentence boundaries shows which side it belongs on.

Semicolons in lists with commas

Semicolons have one more job. When the items in a list already contain commas, semicolons go between the items, including before the final “and.” Here the items don’t have to be full sentences, and a colon can’t do the job.

Put each semicolon where one item ends and the next begins.

Right: The samples came from Reno, Nevada; Salem, Oregon; and Boise, Idaho.
Wrong: The samples came from Reno; Nevada, Salem; Oregon, and Boise, Idaho.

Each city goes with its state. The wrong version puts the semicolons inside the pairs, cutting Reno off from Nevada and Salem from Oregon.

When an item is a name plus a description, the description stays with the name before it, and the semicolon comes after the description: “The panel included Ana Ruiz, a geologist; Tom Lee, a chemist; and Mia Park, a botanist.” A choice that puts a semicolon right after “Tom Lee” cuts him off from his own description.

A colon needs a full sentence before it

Everything before a colon has to be a full sentence.

Right: The crew’s two tools were a compass and a lamp.
Wrong: The crew’s two tools were: a compass and a lamp.

'The crew’s two tools were' can’t stand alone. It’s still waiting to say what they were.

A colon also can’t come right after words that run straight into what follows: “such as,” “including,” “for,” “and,” or a “to” word like “to remove.”

Trap: A list after unfinished words

“The kit held tools such as: a compass and a lamp.” A list follows the colon, which is where lists often go, so the choice looks right. But “The kit held tools such as” is still waiting for its examples.

What to do: Stop at the colon and read only what comes before it. If that leaves a question hanging (such as what?), the colon is wrong.

What can follow a colon

The words after a colon don’t have to be a full sentence. They have to name, explain, or list what the sentence before the colon sets up.

Right: The failure had one cause: a cracked valve.
Wrong: The failure had one cause; a cracked valve.

'A cracked valve' has no verb, so it can’t stand alone, and a semicolon needs a full sentence after it.

Trap: A colon before describing words

“The divers found a clay jar: which still held traces of olive oil.” The left side is a full sentence, so the colon seems fine. But the words after it only describe the jar.

What to do: Ask what the words after the colon do. If they only describe the last thing named, they’re extra words and take a comma: “a clay jar, which still held traces of olive oil.”

A colon after a long left side

Extra words near the start can hide whether the left side is a full sentence, so cross them out before you check.

“The survey, conducted after the spring thaw, focused ______ lower salt levels, warmer water, and weaker currents.”

A. on three changes:
B. on three changes;
C. on: three changes
D. on three changes,

Cross out “conducted after the spring thaw,” and with A in place the left side reads “The survey focused on three changes.” That’s a full sentence, and the list names the changes, so A is right. B’s semicolon needs a full sentence after it, and a list isn’t one. C puts the colon after “on,” which is still waiting for what the survey focused on. D’s comma makes “three changes” look like the first of four items.

Dashes around extra words

The test prints the long dash with no spaces around it, as in the examples here.

Two dashes can fence off extra words in the middle of a sentence. Cross out the dashes and everything between them, and a full sentence has to be left.

Right: The channel—a narrow passage beneath the wall—carried rainwater.
Wrong: The channel—a narrow passage beneath the wall carried rainwater.

The wrong version opens the extra words and never closes them.

“The tablets—clay records recovered from a room beneath the temple ______ several trade agreements.”

A. —describe
B. , describe
C. —, describe
D. describe

Cross out the extra words and you get “The tablets describe several trade agreements.” “Recovered” is a verb too, but it belongs to the extra words about where the records were found. So the blank has to close the extra words and go straight on to “describe,” which is A. B closes a dash with a comma. C closes the pair but then adds a comma between “tablets” and its verb, and D never closes the extra words.

Close a pair with the matching mark

Close extra words with the same mark that opened them, whether that’s a dash, a comma, or a parenthesis.

Right: The tablets (records of local trade) survived.
Wrong: The tablets (records of local trade—survived.

A parenthesis that opens has to close with a parenthesis.

Trap: Half a pair

“The logbook—kept through three winters at a camp on the ice, where planes landed twice a year, remains the only full record.” The opening dash is far back, and after the comma at “ice,” another comma at “year” feels natural.

What to do: Before you choose, look back to the start of the sentence. If a dash or parenthesis is still open, close it with the same mark.

One dash before an explanation

After a full sentence, one dash can introduce words that explain or list, the same way a colon does.

Right: One condition stopped the trial—extreme heat.
Wrong: One condition stopped the trial; extreme heat.

'Extreme heat' has no verb, so it can’t stand alone after a semicolon.

To tell whether a dash needs a partner, read past the extra words. If the sentence keeps going, as in “The channel—a narrow passage beneath the wall—carried rainwater,” close them with a second dash. If the sentence ends with them, as in “One condition stopped the trial—extreme heat,” one dash is enough.

A colon and one dash do the same job here, so if two choices differ only in that mark, neither can be the answer.

Opening words take a comma

Opening words take a comma before the full sentence.

Right: Preserved by dry air, the seeds remained intact.
Wrong: Preserved by dry air; the seeds remained intact.

'Preserved by dry air' can’t stand alone, so it can’t go before a semicolon.

Commas covers the other places a comma goes.

When no mark belongs

No single mark goes between a subject and its verb.

Right: The walls near the northern gate contained older bricks.
Wrong: The walls near the northern gate, contained older bricks.

The whole subject is 'The walls near the northern gate.' A subject that long still takes no mark before its verb.

No mark goes before “that” when the words after it say which ones.

Right: The lab kept only the cores that showed ash layers.
Wrong: The lab kept only the cores: that showed ash layers.

'That showed ash layers' says which cores the lab kept, so it can’t be split off.

The choice with no mark can look too plain to be right, especially in a long sentence. Before you rule it out, try to name the rule that would put a mark at the blank. If you can’t, pick no mark.

Practice

Work the three examples, then try five more. Their explanations use a few grammar names. An is a full sentence. A is a noun with the words attached to it, such as “a cracked valve.” An is extra words that rename the noun just before them.

Worked example

As printing expanded in early modern Europe, book indexes became more common. One especially useful feature helped readers navigate long ______ alphabetical list of subjects followed by the pages where each subject appeared.

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

A
volumes: an
B
volumes; an
C
volumes, an
D
volumes an

Show the answer

A
volumes: an
Correct answer
The before the blank is complete, and “an alphabetical list of followed by the pages where each subject appeared” explains the useful feature. A correctly introduces that explanation.
B
volumes; an
The creates a by treating the beginning “an alphabetical list” as a complete sentence.
C
volumes, an
The does not correctly introduce the that explains what the useful feature was. It also makes the phrase appear to rename the nearby “volumes,” even though the phrase is .
D
volumes an
Without punctuation, the explanatory is incorrectly attached to the complete . A is needed to mark the phrase as an explanation of the useful feature.

Solution

The words before the blank form a complete : “One especially useful feature helped readers navigate long volumes.” The that follows identifies and explains that feature: “an alphabetical list of followed by the pages where each subject appeared.” A correctly follows the complete clause and introduces its explanation, so “volumes: an” completes the sentence.

Report a problem

Worked example

A concert society’s printed program—a folded sheet that listed each selection, identified its composer, named the featured performers, and included brief descriptions of unfamiliar ______ practical information with material that encouraged listeners to compare compositions, recognize recurring musical themes, and discuss the performance with other audience members after leaving the hall. Earlier copies had provided only titles.

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

A
works, combined
B
works—, combined
C
works—combined
D
works combined

Show the answer

A
works, combined
The after “works” does not match the that opens the after “program,” so the required pair is incomplete.
B
works—, combined
The after the closing wrongly separates the “program” from its “combined.”
C
works—combined
Correct answer
The after “works” closes the that begins after “program.” The main then resumes with the “program” and the “combined.”
D
works combined
Without a after “works,” the remains open when the sentence returns to the main with “combined.”

Solution

The is “A concert society’s printed program,” and its is “combined.” The words from “a folded sheet” through “unfamiliar works” form an that describes the program.

Because this appositive opens with a after “program,” it must close with a matching dash after “works.” No should separate the subject from its verb, so the completed sentence reads “unfamiliar works—combined practical information.”

Report a problem

Worked example

Astronomers analyzing historical measurements traced a known planet’s unexpected motion to the pull of an unseen neighbor. Their calculations, despite gaps in records of earlier observations ______ a likely location, an approximate mass, and a probable orbit.

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

A
such as orbital positions, identified the following;
B
such as orbital positions, identified the following,
C
such as orbital positions, identified the following:
D
such as: orbital positions, identified the following

Show the answer

A
such as orbital positions, identified the following;
The leaves a after it: “a likely location, an approximate mass, and a probable orbit” is a list of with no , so it cannot stand as an .
B
such as orbital positions, identified the following,
The after “identified the following” is the wrong punctuation mark. A comma cannot introduce this list after a complete .
C
such as orbital positions, identified the following:
Correct answer
The ending in “identified the following” is complete, and the introduces the list of what the calculations identified. The after “orbital positions” closes the interrupting phrase that begins with “despite.”
D
such as: orbital positions, identified the following
The after “such as” is the wrong punctuation mark because it separates those words from their example, “orbital positions.” The material before that colon is incomplete because the main has not yet reached its , “identified.”

Solution

The of the second sentence is “Their calculations,” and its is “identified.” The phrase beginning with “despite” interrupts that subject and verb, so the after “orbital positions” closes the interruption.

Without the interruption, the sentence reads, “Their calculations identified the following: a likely location, an approximate mass, and a probable orbit.” The words before the form a complete . The colon introduces the list of what the calculations identified.

Report a problem

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5 questions on this skill, with every choice explained.

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Related lessons

Semicolons, colons, and dashes

What the question looks like

Check each side of the blank

A semicolon between full sentences

Semicolons with however and therefore

Semicolons in lists with commas

A colon needs a full sentence before it

What can follow a colon

A colon after a long left side

Dashes around extra words

Close a pair with the matching mark

One dash before an explanation

Opening words take a comma

When no mark belongs

Practice