The rules that solve most questions
- Two complete sentences (independent clauses) can be joined by a period, a semicolon, or a comma plus and, but, or, so, for, nor or yet.
- A comma alone between two complete sentences is a comma splice, always wrong on the SAT.
- A colon follows a complete sentence and introduces a list, an explanation or an example.
- Interrupting phrases are set off on both sides with matching punctuation: two commas or two dashes.
- Never put punctuation between a subject and its verb, or between a verb and its object.
Traps the wrong answers are built on
- A semicolon before a phrase that isn't a complete sentence.
- Closing an interrupting phrase with a different mark than the one that opened it.
Worked example
The honeybee waggle dance tells nestmates where to find food. The angle of the dance relative to vertical indicates the direction of the food source relative to the ______ the duration of the waggle run indicates its distance.
Which choice completes the text so that it conforms to the conventions of Standard English?
- A. sun and,
- B. sun, and
- C. sun, so that
- D. sun
Answer: B. Two independent clauses ("The angle … indicates the direction …" and "the duration … indicates its distance") are joined here. Two independent clauses need a comma plus a coordinating conjunction: "sun, and."
Practice set
Answer each question to see whether you're right and why.
0 of 10 answered · 0 correct
- Question 1Medium
The honeybee waggle dance tells nestmates where to find food. The angle of the dance relative to vertical indicates the direction of the food source relative to the ______ the duration of the waggle run indicates its distance.
Which choice completes the text so that it conforms to the conventions of Standard English?
Show answer and explanation
Answer: B
Two independent clauses ("The angle … indicates the direction …" and "the duration … indicates its distance") are joined here. Two independent clauses need a comma plus a coordinating conjunction: "sun, and."
- A: "sun and," puts the comma after the conjunction, which isn't standard.
- C: "so that" says the second fact happens because of the first, which the passage doesn't claim.
- D: "sun" with no punctuation creates a run-on.
- Question 2Medium
Mount Everest's summit sits on the border between two countries ______ Nepal and China.
Which choice completes the text so that it conforms to the conventions of Standard English?
Show answer and explanation
Answer: C
A colon can introduce a list or explanation after a complete sentence. "Mount Everest's summit sits on the border between two countries" is complete, and "Nepal and China" names them.
- A: "countries, and Nepal and China" makes no grammatical sense.
- B: "Those being Nepal and China" is a fragment.
- D: A semicolon must join two independent clauses; "Nepal and China" is not a clause.
- Question 3Medium
Octopuses can change the color of their skin in a fraction of a second. ______ specialized cells called chromatophores, which expand and contract to show or hide pigment.
Which choice completes the text so that it conforms to the conventions of Standard English?
Show answer and explanation
Answer: D
The second sentence needs a subject and a verb. "They do this with specialized cells …" is a complete sentence.
- A: "With specialized cells …" has no subject or main verb.
- B: "Which they do with …" is a dependent clause standing alone, a fragment.
- C: "Doing this with …" has no main verb, so it's a fragment.
- Question 4Medium
The Great Wall of China was not built all at once. Different dynasties built and rebuilt sections over many centuries ______ much of what visitors see today dates from the Ming dynasty.
Which choice completes the text so that it conforms to the conventions of Standard English?
Show answer and explanation
Answer: A
Both sides are independent clauses, and a semicolon correctly joins two closely related independent clauses.
- B: A comma alone between two independent clauses is a comma splice.
- C: No punctuation creates a run-on sentence.
- D: "which" would make the second part refer to "centuries," and the sentence would no longer make sense.
- Question 5Medium
Marie Curie was the first person to win Nobel Prizes in two different sciences ______ physics in 1903 and chemistry in 1911.
Which choice completes the text so that it conforms to the conventions of Standard English?
Show answer and explanation
Answer: B
A colon after a complete sentence introduces the specifics: "physics in 1903 and chemistry in 1911."
- A: A semicolon needs an independent clause after it; the phrase that follows isn't one.
- C: "Being physics … " is a fragment.
- D: "sciences, they were physics …" is a comma splice.
- Question 6Medium
Tardigrades, tiny animals sometimes called water bears ______ can survive extreme cold, heat and dehydration by entering a dormant state.
Which choice completes the text so that it conforms to the conventions of Standard English?
Show answer and explanation
Answer: C
"tiny animals sometimes called water bears" is an interrupting phrase that begins with a comma, so it must close with a comma too.
- A: A colon would also separate the subject from its verb.
- B: A dash can set off a phrase, but only if a dash opens it too. Here a comma opens it, so it must close with a comma.
- D: A semicolon would split the subject "Tardigrades" from its verb "can survive."
- Question 7Medium
Bats find insects in the dark by echolocation. They emit high-pitched calls and listen for the ______ returning echoes reveal the size and position of nearby objects.
Which choice completes the text so that it conforms to the conventions of Standard English?
Show answer and explanation
Answer: D
"They emit … and listen for the echoes" and "The returning echoes reveal …" are complete sentences; a period separates them correctly.
- A: "and so" would say the echoes reveal positions because the bats listen, which reverses the logic.
- B: A comma alone between them is a comma splice.
- C: No punctuation runs the two sentences together.
- Question 8Medium
The periodic table arranges the chemical elements by atomic number, which is the number of ______ in an atom's nucleus.
Which choice completes the text so that it conforms to the conventions of Standard English?
Show answer and explanation
Answer: A
The sentence ends right after "in an atom's nucleus," so no punctuation belongs between "protons" and "in."
- B: A comma would split "the number of protons" from "in an atom's nucleus," which belong together.
- C: A semicolon needs an independent clause on both sides.
- D: A colon needs a complete sentence before it and an explanation after it.
- Question 9Medium
Venus is the hottest planet in the solar system, even though Mercury is closer to the ______ thick atmosphere of carbon dioxide traps heat.
Which choice completes the text so that it conforms to the conventions of Standard English?
Show answer and explanation
Answer: B
The first sentence is complete after "closer to the Sun," and "Venus's thick atmosphere … traps heat" is a second complete sentence, so a period is correct.
- A: A comma alone joins two independent clauses: a comma splice.
- C: "while" signals a contrast, but the second clause explains the first rather than contrasting with it.
- D: No punctuation is a run-on.
- Question 10Medium
Many deserts are not hot. Antarctica, for example ______ classified as a desert because it receives very little precipitation.
Which choice completes the text so that it conforms to the conventions of Standard English?
Show answer and explanation
Answer: D
"for example" interrupts the sentence, so it needs a comma on both sides: "Antarctica, for example, is classified …"
- A: A colon can't come between a subject and its verb.
- B: Leaving out the comma leaves "for example" half set off.
- C: A semicolon would split the subject from its verb.
More Standard English Conventions practice
Questions people ask
Is this boundaries (punctuation) practice like the real SAT?
The questions follow the format of the digital SAT's Standard English Conventions domain: a short text with one blank or question and four choices. They are written for this site; they are not official College Board questions.
Where is the domain on the test?
Standard English Conventions is one of the four content domains of the SAT Reading and Writing section, alongside Information and Ideas, Craft and Structure, Expression of Ideas.