Original practice packet

SAT Grammar Practice Packet: Clause Boundaries and Sentence Structure

Twelve original grammar questions with a clause decision chart, every-choice explanations, transfer checks and a printable answer key.

Reviewed October 13, 2026

Before you start

Attempt all 12 questions before reading the key. For each blank, underline the main subject and finite verb, then identify whether each side is independent. This is original PeakSAT practice, not an official SAT test or score predictor.

A decision method to use

Read the entire sentence.
Find the main subject and finite verb.
Test whether each side can stand alone.
Two independent clauses: a period, semicolon, or comma plus coordinating conjunction can work.
Introductory dependent clause: use a comma before the main clause.
Colon: first require a complete clause, then an explanation or list.
Check modifiers, agreement and parallelism separately. Do not put punctuation between a subject and its verb or a verb and its object.

Recheck the structure whenever the wording changes.Open full-size image: Clause decision chart: two independent clauses need a strong boundary; an introductory although-clause takes a comma; a subject phrase connects directly to its verb.

Question 1 of 12
Independent clauses
The telescope was small___it revealed unusually faint stars. Which choice creates a conventional boundary?
Choose one answer for question 1
Choice A: commaChoice B: semicolonChoice C: no punctuationChoice D: colon followed by comma
Reveal answer and reasoning for question 1
Correct answer
Choice B: semicolon
Explanation
Each side has a subject, a finite verb and a complete thought. A semicolon joins the related independent clauses.
Why each choice is right or wrong
1. Choice A
  A comma alone splices two independent clauses.
2. Choice B
  , Correct answer
  A semicolon makes a valid boundary between the complete clauses.
3. Choice C
  No punctuation creates a fused sentence.
4. Choice D
  A colon followed immediately by a comma is not a conventional boundary.
Fresh check
Join “The battery was charged” and “the sensor resumed recording” with one mark.
Show the check answer for question 1
Answer
semicolon
Why
Both clauses are independent, so a semicolon works. A period would also work if the second clause were capitalized.
Question 2 of 12
Introductory dependent clauses
Although the archive opened late___the visitors completed their research. Which choice fits?
Choose one answer for question 2
Choice A: semicolonChoice B: commaChoice C: colonChoice D: no punctuation
Reveal answer and reasoning for question 2
Correct answer
Choice B: comma
Explanation
Although makes the opening clause dependent. An introductory dependent clause is followed by a comma before the main clause.
Why each choice is right or wrong
1. Choice A
  A semicolon requires an independent clause on each side here.
2. Choice B
  , Correct answer
  A comma separates the introductory dependent clause from the independent main clause.
3. Choice C
  A colon should follow a complete clause; this opening is dependent.
4. Choice D
  Omitting the boundary fails to separate the introductory clause conventionally.
Fresh check
Complete: “Because the labels had faded___the curator replaced them.”
Show the check answer for question 2
Answer
comma
Why
Because creates an introductory dependent clause. It is followed by a comma.
Question 3 of 12
Conjunctive adverbs
The first batch failed___however, the revised process produced a usable sample. Which choice fits?
Choose one answer for question 3
Choice A: commaChoice B: no punctuationChoice C: semicolonChoice D: semicolon followed by comma
Reveal answer and reasoning for question 3
Correct answer
Choice C: semicolon
Explanation
However is a transition, not a coordinating conjunction. The two independent clauses need a strong boundary; the existing comma sets off however.
Why each choice is right or wrong
1. Choice A
  A comma alone creates a comma splice.
2. Choice B
  No punctuation creates a fused sentence.
3. Choice C
  , Correct answer
  A semicolon separates the independent clauses; the comma after however is already supplied.
4. Choice D
  The extra comma immediately after the semicolon has no grammatical role.
Fresh check
Complete: “The original route was blocked___therefore, the hikers took a detour.”
Show the check answer for question 3
Answer
semicolon
Why
Therefore is a conjunctive adverb between two complete clauses.
Question 4 of 12
Coordinating conjunctions
The sound was faint___but the microphone captured it clearly. Which choice fits?
Choose one answer for question 4
Choice A: commaChoice B: semicolon followed by commaChoice C: colon followed by commaChoice D: no punctuation
Reveal answer and reasoning for question 4
Correct answer
Choice A: comma
Explanation
But is a coordinating conjunction joining two independent clauses. A comma before but makes the standard boundary.
Why each choice is right or wrong
1. Choice A
  , Correct answer
  A comma followed by but joins the complete clauses conventionally.
2. Choice B
  The semicolon-comma combination is unnecessary and invalid here.
3. Choice C
  The colon-comma combination is not a conventional boundary.
4. Choice D
  These two independent clauses call for a comma before but in this construction.
Fresh check
Complete: “The gate was locked___so the team used another entrance.”
Show the check answer for question 4
Answer
comma
Why
So joins two independent clauses as a coordinating conjunction.
Question 5 of 12
Colons introducing explanations
The kit contained three essentials___a ruler, a compass, and a notebook. Which choice conventionally introduces the list?
Choose one answer for question 5
Choice A: colonChoice B: semicolonChoice C: no punctuationChoice D: , and
Reveal answer and reasoning for question 5
Correct answer
Choice A: colon
Explanation
The words before the blank form a complete clause. A colon introduces the list that identifies the three essentials.
Why each choice is right or wrong
1. Choice A
  , Correct answer
  A colon follows a complete clause and introduces its explanatory list.
2. Choice B
  The list is not an independent clause, so a semicolon does not work.
3. Choice C
  The list needs a boundary after the complete opening clause.
4. Choice D
  And does not connect the list conventionally to the preceding complete sentence in this wording.
Fresh check
May a colon follow “The kit contained” before a list?
Show the check answer for question 5
Answer
No.
Why
That would separate the verb from its objects. “The kit contained a ruler, a compass, and a notebook” needs no colon.
Question 6 of 12
Essential modifiers
The students___who completed the safety training___could use the laboratory. The writer means only the trained students. Which punctuation fits both blanks?
Choose one answer for question 6
Choice A: commas in bothChoice B: no punctuation in eitherChoice C: a semicolon in eachChoice D: a colon in each
Reveal answer and reasoning for question 6
Correct answer
Choice B: no punctuation in either
Explanation
Who completed the safety training restricts which students are meant. An essential modifier is not enclosed in commas.
Why each choice is right or wrong
1. Choice A
  Commas would present the modifier as extra information and change the intended restriction.
2. Choice B
  , Correct answer
  No commas preserve the restriction to trained students.
3. Choice C
  Semicolons cannot separate this relative clause from its noun and main verb.
4. Choice D
  Colons do not enclose a restrictive relative clause.
Fresh check
Does “The students, who completed the training, entered” restrict the statement to a subgroup?
Show the check answer for question 6
Answer
No.
Why
The comma-enclosed modifier presents the training as additional information about the identified students.
Question 7 of 12
Nonessential appositives
The expedition leader___a skilled navigator___charted a new route. Which paired punctuation treats the middle phrase as extra description?
Choose one answer for question 7
Choice A: no punctuationChoice B: commasChoice C: semicolonsChoice D: a colon then no mark
Reveal answer and reasoning for question 7
Correct answer
Choice B: commas
Explanation
A skilled navigator is a nonessential appositive describing the already identified leader. It needs matching boundaries on both sides.
Why each choice is right or wrong
1. Choice A
  Without boundaries, the inserted appositive is not set off.
2. Choice B
  , Correct answer
  Matching commas enclose the appositive.
3. Choice C
  Semicolons are not boundaries for this phrase.
4. Choice D
  A colon after the subject interrupts the subject-verb connection, and the phrase lacks a closing boundary.
Fresh check
Remove the appositive from the original sentence. What remains?
Show the check answer for question 7
Answer
The expedition leader charted a new route.
Why
The remaining complete sentence confirms that the inserted description is structurally optional.
Question 8 of 12
Subject-verb boundaries
The analysis of the samples___revealed a previously unnoticed pattern. Which choice fits?
Choose one answer for question 8
Choice A: commaChoice B: semicolonChoice C: colonChoice D: no punctuation
Reveal answer and reasoning for question 8
Correct answer
Choice D: no punctuation
Explanation
The main subject is analysis, followed by its verb revealed. The intervening prepositional phrase does not create a punctuation boundary.
Why each choice is right or wrong
1. Choice A
  A comma would unnecessarily separate the subject from its verb.
2. Choice B
  The text before the blank is only the subject phrase, not a complete clause.
3. Choice C
  A colon would interrupt the subject-verb connection.
4. Choice D
  , Correct answer
  No punctuation keeps the main subject connected to its verb.
Fresh check
Identify the subject and verb in “The color of the stones changed.”
Show the check answer for question 8
Answer
Subject: color. Verb: changed.
Why
Of the stones modifies color; it does not create a separate clause.
Question 9 of 12
Relative clauses versus main verbs
The instrument, which measures tiny vibrations, ___ sensitive enough to detect the signal. Which choice makes a complete grammatical sentence?
Choose one answer for question 9
Choice A: beingChoice B: isChoice C: to beChoice D: and
Reveal answer and reasoning for question 9
Correct answer
Choice B: is
Explanation
Measures belongs to the relative clause. The main subject instrument still needs the finite main verb is.
Why each choice is right or wrong
1. Choice A
  Being alone is not a finite main verb.
2. Choice B
  , Correct answer
  Is supplies the required singular finite main verb.
3. Choice C
  To be is an infinitive and cannot serve as the main finite verb here.
4. Choice D
  And supplies neither a verb nor a complete predicate.
Fresh check
Complete: “The instruments, which measure tiny vibrations, ___ sensitive.”
Show the check answer for question 9
Answer
are
Why
The plural main subject instruments requires are. The verb within which-clause does not replace the main verb.
Question 10 of 12
Participial modifiers
Carrying the replacement lens, ___ entered the observatory. Which completion avoids a dangling modifier?
Choose one answer for question 10
Choice A: the caseChoice B: the technicianChoice C: thereChoice D: the observatory door
Reveal answer and reasoning for question 10
Correct answer
Choice B: the technician
Explanation
The introductory phrase describes the person carrying the lens. The main subject should identify that person.
Why each choice is right or wrong
1. Choice A
  A case is not the intended person carrying the lens.
2. Choice B
  , Correct answer
  The technician is the logical doer of carrying and entered.
3. Choice C
  There does not identify a person carrying the lens.
4. Choice D
  A door cannot perform the described actions.
Fresh check
Repair: “Walking toward the lab, the notebook fell from Maya’s bag.”
Show the check answer for question 10
Answer
As Maya walked toward the lab, the notebook fell from her bag.
Why
The revision explicitly assigns walking to Maya rather than the notebook.
Question 11 of 12
Agreement across phrases
Each of the sketches ___ a different stage of the design. Choose the correct present-tense verb.
Choose one answer for question 11
Choice A: showChoice B: showsChoice C: are showingChoice D: have shown
Reveal answer and reasoning for question 11
Correct answer
Choice B: shows
Explanation
The main subject each is singular. Of the sketches is a modifying phrase, so the plural sketches does not control agreement.
Why each choice is right or wrong
1. Choice A
  Show does not agree with singular each in this sentence.
2. Choice B
  , Correct answer
  Shows is the singular present-tense form.
3. Choice C
  Are is plural and does not agree with each.
4. Choice D
  Have is plural here and also changes the requested tense.
Fresh check
Complete: “Several of the sketches ___ a different stage.”
Show the check answer for question 11
Answer
show
Why
Several is plural. Changing each to several changes the controlling subject.
Question 12 of 12
Parallel structure
The workshop teaches students to observe carefully, to record measurements, and ___. Which choice completes the parallel list?
Choose one answer for question 12
Choice A: analyzing resultsChoice B: analysis of resultsChoice C: to analyze resultsChoice D: results are analyzed
Reveal answer and reasoning for question 12
Correct answer
Choice C: to analyze results
Explanation
The first two list items are infinitive phrases. To analyze results gives the third item the same grammatical form.
Why each choice is right or wrong
1. Choice A
  The -ing phrase breaks the established infinitive pattern.
2. Choice B
  The noun phrase breaks the pattern.
3. Choice C
  , Correct answer
  The infinitive phrase matches to observe and to record.
4. Choice D
  The independent clause changes both structure and subject.
Fresh check
Complete the alternative list: “observing carefully, recording measurements, and ___.”
Show the check answer for question 12
Answer
analyzing results
Why
Here all three items use -ing phrases. Parallelism depends on the actual pattern.

Keep going with sentence boundaries practice and form structure sense practice, or print the full packet (PDF): SAT Grammar Practice Packet: Clause Boundaries and Sentence Structure.

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Before you start

A decision method to use

Attempt the 12 questions

Question 1 of 12

Question 2 of 12

Question 3 of 12

Question 4 of 12

Question 5 of 12

Question 6 of 12

Question 7 of 12

Question 8 of 12

Question 9 of 12

Question 10 of 12

Question 11 of 12

Question 12 of 12

Downloads

Use this packet in class or at home

Sources