Boundaries
Explanation
Boundaries questions give you a short sentence or two with a blank, followed by the prompt “Which choice completes the text so that it conforms to the conventions of Standard English?”
These questions test how correctly a sentence is divided and punctuated. Four conventions come up repeatedly: linking main clauses (two independent clauses can be joined with a semicolon, or with a comma followed by a coordinating conjunction such as “and,” but never with a comma alone—a comma splice—or with no punctuation at all—a run-on); supplementary elements (a non-essential phrase, definition, or example must be set off from the rest of the sentence with a matching pair of commas, or fully enclosed in parentheses, not left with punctuation on only one side); punctuation between a job title and a name (no comma or colon ever separates a title like “Chemist” from the proper noun it describes, such as “Chemist Elena Popov”); and end-of-sentence punctuation for indirect questions (a sentence that reports what someone investigated or wondered about, rather than directly asking the question, ends with a period, not a question mark).
Example 1
Example 2
Tips for solving
- First identify whether the material on each side of the blank is a complete independent clause or an incomplete supplementary phrase—the correct punctuation depends entirely on this distinction.
Example: The team spent months analyzing the satellite imagery ____ discovering several previously unmapped archaeological sites in the Amazon basin.
Independent Clause Check:
Left side: "The team spent months analyzing the satellite imagery" (Complete clause).
Right side: "discovering several previously unmapped archaeological sites in the Amazon basin" (Incomplete supplementary phrase starting with a participle).
Incorrect Choice: imagery; discovering (Uses a semicolon before an incomplete phrase).
Correct Choice: imagery, discovering (Uses a comma to connect an independent clause to a dependent supplementary phrase).
- Two independent clauses can be joined only with a semicolon, or with a comma plus a coordinating conjunction (and, but, or, so, yet); a comma alone creates a comma splice, and no punctuation at all creates a run-on.
Example: The new solar-powered turbine generates electricity during the day ____ it stores excess energy in lithium batteries for use at night.
Clause Check:
Left side: "The new solar-powered turbine generates electricity during the day" (Independent clause).
Right side: "it stores excess energy in lithium batteries for use at night" (Independent clause).
Comma Splice Trap: day, it stores (Incorrectly joins two full clauses with just a comma).
Run-On Trap: day it stores (Joins two full clauses with zero punctuation).
Correct Choice: day; it stores OR day, and it stores
- Never use a semicolon to attach a non-essential phrase (one starting with words like "including," "among," or "such as") to a main clause; a semicolon requires a full independent clause on both sides.
Example: Several invasive marine species have adapted remarkably well to warming coastal waters ____ including the European green crab and the Asian shore crab.
Semicolon Trap Choice: waters; including the European green crab (Incorrect because the text after the semicolon is a list phrase, not an independent clause).
Correct Choice: waters, including the European green crab
- A supplementary phrase, definition, or example set in the middle of a sentence needs punctuation on both sides to match—a comma before and a comma after, or fully enclosed in parentheses—never punctuation on just one side.
Example: Dr. Aris Thorne ____ a leading authority on geothermal activity ____ presented his research at the international geology summit.
One-Sided Punctuation Trap: Dr. Aris Thorne, a leading authority on geothermal activity presented (Missing the matching comma after "activity").
Correct Choice: Dr. Aris Thorne, a leading authority on geothermal activity, presented OR Dr. Aris Thorne (a leading authority on geothermal activity) presented
- Never place a comma or colon between a professional title and the proper name it describes; titles like "Biologist" or "Senator" attach directly to the name with no punctuation.
Example: Climatologist ____ published a landmark study detailing the rate of glacial melt in Antarctica.
Punctuation Trap Choice: Climatologist, Dr. Elena Rostova, published (Incorrectly places commas around/after the name following a title).
Colon Trap Choice: Climatologist: Dr. Elena Rostova published
Correct Choice: Climatologist Dr. Elena Rostova published (Zero punctuation between job title and proper name).
- Likewise, don’t place a comma between that title-plus-name subject and the verb that follows it.
Example: Marine ecologist Dr. Marcus Vance ____ that overfishing has drastically altered coral reef food webs.
Punctuation Trap Choice: Marine ecologist Dr. Marcus Vance, argued (Puts an unnecessary comma between the full subject and the main verb "argued").
Correct Choice: Marine ecologist Dr. Marcus Vance argued (No comma separating the subject from its verb).
- When a sentence reports what someone studied, wondered, or investigated (an indirect question), end it with a period; reserve the question mark for a directly quoted or directly asked question.