Digital SAT · Boundaries
How to Solve Attaching a Dependent Clause on the Digital SAT
One side of the boundary is a complete sentence and the other is a dependent clause, one that cannot stand alone. The punctuation depends on which side is which. A dependent clause at the front usually attaches with a comma; the same clause at the end often needs no comma at all. Because one side is a fragment, a semicolon is wrong, since semicolons join two complete clauses. Testing each side for completeness is what tells you the mark.
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- Medium typical difficulty
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- 100 practice questions
Frequency reflects how often this question type appears on a full-length Digital SAT. The difficulty mix reflects every question of this type across our bank.
What the question bank shows
Because a dependent clause is incomplete, a semicolon cannot join the two parts.
A leading dependent clause takes a comma; a trailing essential one usually does not.
A subordinating word marks the dependent side and sets the punctuation.
How to recognize attaching a dependent clause questions
- One side of the choice is a fragment beginning with a word like because, although, or which.
- The other side is a complete sentence.
- The choices vary the comma and sometimes offer a semicolon.
- The prompt tests how the two parts attach, not word choice.
Why students miss these
The step-by-step method
- 1
Test each side
Read both halves separately and mark which is complete and which is dependent.
- 2
Rule out the semicolon
If either side is a fragment, a semicolon cannot join them.
- 3
Place the comma by position
A dependent clause in front takes a comma; the same clause at the end usually takes none.
- 4
Reread for flow
Confirm the join reads as one clear sentence, not a run-on or a splice.
Worked examples
Easy example
Few foods can survive for thousands of years, but one remarkable exception exists. Archaeologists exploring ancient Egyptian tombs have found sealed clay pots of ______ remained perfectly edible despite being many thousands of years old.
A: Incorrect. A semicolon must separate two independent clauses, but "which remained perfectly edible ..." is a dependent relative clause.
B: Correct. A comma sets off the nonrestrictive relative clause beginning with "which," attaching it to the main clause.
C: Incorrect. A period creates a sentence fragment, since "Which remained perfectly edible ..." cannot stand alone.
D: Incorrect. Without the comma, the relative clause runs into the main clause without the punctuation a nonrestrictive clause requires.
Explanation
The clause beginning with "which" is a dependent, nonrestrictive relative clause, so it is attached to the main clause with a comma rather than a semicolon or period.
Easy example
Monarch butterflies travel thousands of miles each autumn to reach their warmer wintering grounds in central Mexico. Because the remarkable journey is far too long for any single ______ completes only one leg before the next generation continues the migration.
A: Incorrect. The introductory 'Because' clause needs a comma before the main clause; omitting all punctuation runs the two parts together.
B: Incorrect. A semicolon must join two independent clauses, but 'Because the remarkable journey is far too long for any single butterfly' cannot stand alone.
C: Incorrect. A period would create two sentences, but the introductory 'Because' clause is a fragment that cannot stand by itself.
D: Correct. The opening element beginning 'Because' is a dependent clause, so a comma is the conventional mark attaching it to the independent clause 'it completes only one leg.'
Explanation
A dependent 'Because' clause opens the sentence, so a comma must link it to the independent clause.
Easy example
Giant sequoias grow naturally only on the western slopes of California's Sierra Nevada. These towering trees can live for more than three thousand ______ lifespan that allows them to survive droughts, fires, and other threats over the long centuries of their growth.
A: Incorrect. Without punctuation the appositive 'a lifespan that allows...' runs into 'years' and is not set off from it.
B: Correct. The phrase 'a lifespan that allows them to survive...' renames 'three thousand years,' so a comma sets off this appositive.
C: Incorrect. A colon introduces a list or explanation; here the phrase renames the span of years, so a comma is needed instead.
D: Incorrect. A semicolon joins two complete sentences, but 'a lifespan that allows...' is only a phrase, not a clause.
Explanation
The material after the blank renames 'three thousand years.' A nonrestrictive appositive takes a comma, so 'years, a' is correct; the colon, semicolon, and missing comma all fail to set off the phrase.
The common traps
| Pattern | What it does | The tell |
|---|---|---|
| Semicolon on a fragment | Joined a dependent clause with a semicolon. | A semicolon needs two complete sentences; a dependent side rules it out. |
| Missing lead-in comma | Dropped the comma after a front dependent clause. | A dependent clause that opens the sentence takes a comma before the main clause. |
| Needless trailing comma | Added a comma before a dependent clause at the end that does not need one. | A trailing essential dependent clause usually takes no comma. |
Try it: two real questions
Jane Goodall began her famous study of wild chimpanzees in Gombe, Tanzania, in 1960. Her patient observations revealed that the chimps use simple ______ overturned a long-held scientific belief that only human beings made and used tools.
Which choice completes the text so that it conforms to the conventions of Standard English?
Maria Mitchell was the first professional female astronomer in the United States and a respected professor. In 1847 she became famous for discovering a ______ earned her a gold medal from the king of Denmark and lasting international fame.
Which choice completes the text so that it conforms to the conventions of Standard English?
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Common questions
How do you punctuate a dependent clause on the SAT?
Check which side is complete. A dependent clause at the start attaches with a comma; at the end it often needs none. A semicolon is wrong because one side is not a full sentence.
Why can't I use a semicolon here?
A semicolon joins two independent clauses. In these items one side is a dependent clause, a fragment, so the semicolon has nothing complete to link to on that side and is incorrect.
When does a trailing dependent clause need a comma?
Usually it does not. If the clause is essential to the meaning, no comma is used. A comma appears mainly when the trailing clause is a nonessential aside, which is less common.
How do I spot a dependent clause?
It often begins with a subordinating word such as because, although, since, when, or a relative word like which. Read it alone; if it cannot stand as a sentence, it is dependent.
Practice attaching a dependent clause the way it is tested
Start with the free 16-question diagnostic, then drill this type with step-by-step reasoning on every question.
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