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4.1 Sentence Boundaries: Fragments, Run-ons, and Comma Splices

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1 Chapter 1: ACCUPLACER Suite Overview & Testing Mechanics

1.1 The ACCUPLACER Testing System & Computer-Adaptive Mechanics 1.2 Placement Policies, Score Scales & Institutional Cut Scores 1.3 Test-Taking Strategies, Tool Mechanics & Pacing

2 Chapter 2: Next-Generation Reading

2.1 The Reading Test Blueprint: Set-Based and Discrete Items 2.2 Information and Ideas: Close Reading & Central Themes 2.3 Summarizing and Understanding Relationships 2.4 Rhetoric, Text Structure & Author's Purpose 2.5 Analyzing Point of View and Authorial Purpose 2.6 Analyzing Arguments: Claims, Counterclaims, and Evidence 2.7 Synthesis & Paired Text Comparative Analysis 2.8 Vocabulary in Context & Figurative Language 2.9 Passage Genre, Content Area, Mode, and Text Complexity 2.10 Answer-Choice Traps and Evidence Discipline

3 Chapter 3: Next-Generation Writing: Expression of Ideas

3.1 The Writing Test Blueprint: Passage Sets and Content Distribution 3.2 Development: Proposition and Supporting Evidence 3.3 Focus: Adding, Retaining, and Deleting for Relevance 3.4 Organization: Logical Sequence and Paragraph Order 3.5 Introductions, Conclusions, and Transitional Cohesion 3.6 Effective Language Use: Precision and Word Choice 3.7 Concision: Eliminating Wordiness and Redundancy 3.8 Style, Tone, and Voice Consistency 3.9 Syntax: Sentence Combining for Rhetorical Purpose

4 Chapter 4: Next-Generation Writing: Standard English Conventions

4.1 Sentence Boundaries: Fragments, Run-ons, and Comma Splices 4.2 Subordination and Coordination 4.3 Parallel Structure 4.4 Modifier Placement: Misplaced and Dangling Modifiers 4.5 Inappropriate Shifts in Verb Tense 4.6 Inappropriate Shifts in Verb Voice and Mood 4.7 Inappropriate Shifts in Pronoun Person and Number 4.8 Subject-Verb Agreement, Pronoun Case, and Verb Forms 4.9 Possessive Determiners, Contractions, and Confusable Adverbs 4.10 Pronoun Clarity and Pronoun-Antecedent Agreement 4.11 Frequently Confused Words, Noun Agreement, and Logical Comparison 4.12 Within-Sentence Punctuation: Semicolons, Colons, Dashes, and Apostrophes 4.13 Items in a Series and Nonrestrictive Elements 4.14 End-of-Sentence Punctuation, Hyphenation, and Unnecessary Punctuation

5 Chapter 5: Next-Generation Arithmetic

5.1 Whole Number Operations, Estimation & Multi-Step Applications 5.2 Fractions, Mixed Numbers & Operations 5.3 Decimal Operations & Place-Value Conversions 5.4 Percent Calculations, Increase, Decrease, and Applications 5.5 Number Comparisons and Equivalents Across Formats

6 Chapter 6: Next-Generation Quantitative Reasoning, Algebra, and Statistics (QAS)

6.1 Rational Numbers, Absolute Value, and Order of Operations 6.2 Exponents, Radicals, and Scientific Notation 6.3 Ratio, Proportional Relationships, and Unit Conversions 6.4 Creating and Evaluating Algebraic Expressions 6.5 Linear Equations, Inequalities, and Systems of Two Equations 6.6 Linear Applications, Functions, and Graphs 6.7 Probability and Sets 6.8 Descriptive Statistics: Center, Spread, and Graphical Displays 6.9 Geometry for Pre-Algebra and Algebra 1

7 Chapter 7: Next-Generation Advanced Algebra, Quadratics & Polynomials

7.1 Advanced Linear Equations, Systems, and Coordinate Geometry 7.2 Factoring Methods for Quadratics, Cubics, and Polynomials 7.3 Quadratic Equations, Vertex Form & Parabolic Functions 7.4 Polynomial Equations, Roots, and Graphs 7.5 Radical and Rational Equations and Functions 7.6 Geometry for Algebra 1 and Algebra 2

8 Chapter 8: Functions, Exponentials, Logarithms & Trigonometry

8.1 Function Notation, Transformations, Compositions & Inverses 8.2 Domain, Range, and Interpreting Functions in Context 8.3 Exponential & Logarithmic Functions, Laws & Modeling 8.4 Right-Triangle Trigonometry, the Unit Circle, and Radian Measure 8.5 Law of Sines, Law of Cosines, and Trigonometric Equations 8.6 Choosing Your Math Test: Arithmetic, QAS, or AAF

9 Chapter 9: WritePlacer & WritePlacer ESL Essays

9.1 WritePlacer Prompt Format, Planning, and the Writing Process 9.2 The WritePlacer Scoring Rubric & 6 Core Dimensions 9.3 Reading the WritePlacer Score Scale: What Each Band Demonstrates 9.4 Essay Architecture: Thesis, Evidence Integration & Structure 9.5 WritePlacer ESL Scoring Standards & Synthesis

10 Chapter 10: ACCUPLACER ESL Placement Suite

10.1 The ESL Placement Suite: Structure, Scoring, and Score Interpretation 10.2 ESL Reading Skills & Passage Comprehension 10.3 ESL Sentence Meaning & Context Clues 10.4 ESL Language Use & Grammatical Mechanics 10.5 ESL Listening Comprehension & Spoken Contexts

4.1 Sentence Boundaries: Fragments, Run-ons, and Comma Splices

Key Takeaways Explain This Topic AI

Every grammatically complete independent clause must possess a subject, a finite conjugated predicate verb, and express an autonomous thought.

Sentence fragments result from missing subjects, standalone verbal phrases (participles or infinitives lacking auxiliary verbs), or stranded subordinate clauses beginning with subordinating conjunctions.

A comma splice occurs when two independent clauses are joined solely by a comma; joining independent clauses with a comma and a conjunctive adverb (e.g., 'however', 'therefore') is also an illegal comma splice.

The four standard methods to repair comma splices and run-ons are: (1) full stop period, (2) semicolon, (3) comma plus coordinating conjunction (FANBOYS), or (4) subordination.

Conjunctive adverbs (however, furthermore, consequently) require a semicolon before them and a comma after them when linking independent clauses: 'Clause; however, clause.'

Last updated: August 2026

Sentence Structure, Boundaries, Fragments & Run-ons

Core ACCUPLACER Concept: On the Next-Generation ACCUPLACER Writing section, Standard English Conventions questions assess your command of the structural foundations of edited American English. Mastery of sentence boundaries—recognizing where one complete thought ends and another begins—is the single most heavily tested syntactic skill. You must be able to instantly diagnose sentence fragments, fused run-on sentences, and comma splices, and apply the appropriate punctuation or conjunction to restore grammatical integrity.

College-level academic writing demands clarity and structural precision. When sentence boundaries break down, the logical relationships between claims, evidence, and qualifiers collapse into ambiguity. To excel on the ACCUPLACER, you must look past the superficial "sound" or rhythm of a sentence and dissect its underlying syntactic anatomy.

1. Anatomy of Clauses: Independent vs. Dependent

At the foundation of all sentence structure lies the clause —a syntactic unit containing a subject and a predicate verb. Clauses are categorized into two fundamental types: ┌─────────────────────────────────────────────────────────────────────────┐

  • │ CLAUSE TAXONOMY │
  • ├────────────────────────────────────┬────────────────────────────────────┤
  • │ INDEPENDENT CLAUSE │ DEPENDENT CLAUSE │
  • ├────────────────────────────────────┼────────────────────────────────────┤
  • │ • Expresses a complete thought │ • Cannot stand alone as a sentence │
  • │ • Contains a subject & finite verb │ • Introduced by a subordinator │
  • │ • Can stand alone as a sentence │ • Leaves the reader hanging │
  • │ │ │
  • │ Example: │ Example: │
  • │ "The turbine generates power." │ "Although the turbine generates..."│
  • └────────────────────────────────────┴────────────────────────────────────┘
  • The Three Requirements of an Independent Clause

An independent clause must satisfy three strict grammatical criteria:

A Grammatical Subject: A noun, pronoun, or noun phrase that performs or receives the action ( "The atmospheric pressure..." ).

A Finite Predicate Verb: A conjugated verb that expresses tense, person, and number ( "...dropped sharply." ). Verbals such as infinitives ( to drop ) or bare present participles ( dropping ) cannot serve as finite verbs without an auxiliary ( was dropping ).

A Complete Thought: The clause must not be subordinated by an introductory dependent marker that leaves the syntactic premise unresolved.

Dependent (Subordinate) Clauses and Markers

A dependent clause contains both a subject and a verb, but it begins with a subordinating conjunction or a relative pronoun . This marker converts the clause into an adverbial, adjectival, or nominal modifier that relies on an independent clause for syntactic completion.

Subordinating Conjunctions: after, although, as, because, before, even though, if, since, so that, though, unless, until, when, whenever, where, whereas, while, whether.

Relative Pronouns: who, whom, whose, which, that, whoever, whomever.

2. Sentence Classification & Syntactic Architecture

Standard English recognizes four primary structural configurations based on clause combinations: 1. SIMPLE SENTENCE:

  • [Independent Clause]
  • Example: "The seismograph recorded subterranean tremors."

2. COMPOUND SENTENCE:

  • [Independent Clause] + [ , Coordinating Conjunction ] + [Independent Clause]
  • OR
  • [Independent Clause] + [ ; ] + [Independent Clause]
  • Example: "The seismograph recorded tremors, and the geologists evacuated the valley."

3. COMPLEX SENTENCE:

  • [Dependent Clause] + [ , ] + [Independent Clause]
  • OR
  • [Independent Clause] + [Dependent Clause]
  • Example: "Because the seismograph recorded tremors, geologists evacuated the valley."

4. COMPOUND-COMPLEX SENTENCE:

  • [Dependent Clause] + [ , ] + [Independent Clause] + [ , Coordinating Conjunction ] + [Independent Clause]
  • Example: "Because tremors intensified, geologists evacuated the valley, but the volcano remained dormant."
  • 3. Diagnosing and Eliminating Sentence Fragments

A sentence fragment is an incomplete syntactic unit punctuated as if it were an independent sentence. On the ACCUPLACER, fragments generally appear in four distinct disguises:

Archetype 1: The Missing Subject Fragment

Occurs when a compound predicate or descriptive phrase is severed from the primary subject by a period.

❌ Fragment: "The aerospace engineers calibrated the optical sensors. And tested the propulsion modules under cryogenic conditions."

✔️ Corrected: "The aerospace engineers calibrated the optical sensors and tested the propulsion modules under cryogenic conditions."

Archetype 2: The Standalone Verbal Fragment (Participle or Infinitive)

Occurs when a participial phrase (-ing / -ed) or an infinitive phrase (to + verb) is mistaken for a complete predicate.

❌ Fragment: "The deep-sea submersible descending past four thousand meters into the abyssal trench."

✔️ Corrected (Adding Finite Auxiliary): "The deep-sea submersible was descending past four thousand meters into the abyssal trench."

✔️ Corrected (Attaching to Main Clause): "Descending past four thousand meters into the abyssal trench, the deep-sea submersible collected water samples."

Archetype 3: The Stranded Subordinate Clause

Occurs when a dependent clause beginning with a subordinating conjunction or relative pronoun is punctuated with a terminal period.

❌ Fragment: "Although the pharmaceutical clinical trial demonstrated a significant reduction in patient symptoms over the twelve-week evaluation period."

✔️ Corrected: "Although the pharmaceutical clinical trial demonstrated a significant reduction in patient symptoms over the twelve-week evaluation period, researchers cautioned that long-term safety data remained preliminary."

Archetype 4: The Appositive / Exemplification Fragment

Occurs when an explanatory list or noun phrase beginning with such as, including, especially, or for example is punctuated as a standalone sentence.

❌ Fragment: "The expedition cataloged several endangered alpine flora. Including the glacial buttercup and the dwarf mountain lupine."

✔️ Corrected: "The expedition cataloged several endangered alpine flora, including the glacial buttercup and the dwarf mountain lupine."

4. Run-on Sentences and Comma Splices

A run-on sentence occurs when two or more independent clauses are joined without adequate punctuation or coordinating conjunctions. Run-on errors manifest in two distinct forms: ┌─────────────────────────────────────────────────────────────────────────┐

  • │ RUN-ON VARIETIES │
  • ├────────────────────────────────────┬────────────────────────────────────┤
  • │ FUSED SENTENCE │ COMMA SPLICE │
  • ├────────────────────────────────────┼────────────────────────────────────┤
  • │ Two independent clauses placed │ Two independent clauses joined │
  • │ side-by-side with zero punctuation │ solely by a comma without a │
  • │ between them. │ coordinating conjunction. │
  • │ │ │
  • │ Example: │ Example: │
  • │ "The spectrometer malfunctioned │ "The spectrometer malfunctioned, │
  • │ the technicians recalibrated it." │ the technicians recalibrated it." │
  • └────────────────────────────────────┴────────────────────────────────────┘
  • The Conjunctive Adverb Trap (The Pseudo-Conjunction)

The most frequent comma splice trap on the ACCUPLACER involves conjunctive adverbs and transitional phrases . Words such as however, therefore, furthermore, moreover, consequently, nevertheless, thus, and phrases like in fact, as a result, on the other hand are adverbs— they are not conjunctions . They possess zero grammatical power to connect independent clauses.

❌ Illegal Comma Splice: "The solar array generated surplus electricity during peak daylight hours, however the local utility grid lacked adequate storage capacity."

✔️ Corrected (Semicolon + Comma): "The solar array generated surplus electricity during peak daylight hours; however, the local utility grid lacked adequate storage capacity."

✔️ Corrected (Period): "The solar array generated surplus electricity during peak daylight hours. However, the local utility grid lacked adequate storage capacity."

5. The Four Legitimate Methods of Splice & Run-on Repair

When you identify two independent clauses improperly connected, you must apply one of the four standard grammatical repair methods. The ACCUPLACER will present answer choices testing each approach; your task is to choose the grammatically sound option that best preserves the author's rhetorical intent. FOUR METHODS TO REPAIR COMMA SPLICES

  • │
  • ┌────────────────┬───────────┴───────────┬────────────────┐
  • ▼ ▼ ▼ ▼
  • [1. PERIOD] [2. SEMICOLON] [3. COMMA + [4. SUBORDINATION]
  • Separate into Join closely related FANBOYS] Convert one clause
  • two distinct clauses (optional Coordinate with into a dependent
  • sentences. conjunctive adverb) proper relation clause modifier
  • Method 1: Full Stop (Period)

Separate the independent clauses into two distinct grammatical sentences. Best used when each clause expresses an independent, detailed assertion.

  • "The archaeological team excavated the ancient citadel. They cataloged hundreds of bronze artifacts."
  • Method 2: Semicolon (Standalone or with Conjunctive Adverb)

Join two closely related independent clauses. A semicolon functions as a soft period, signaling an intimate conceptual relationship between the assertions.

Standalone Semicolon: "The archaeological team excavated the ancient citadel; they cataloged hundreds of bronze artifacts."

With Conjunctive Adverb: "The archaeological team excavated the ancient citadel; consequently, historians revised their timeline of the region."

Method 3: Comma + Coordinating Conjunction (FANBOYS)

Join the clauses using a comma followed immediately by one of the seven coordinating conjunctions: F or, A nd, N or, B ut, O r, Y et, S o.

"The archaeological team excavated the ancient citadel, and they cataloged hundreds of bronze artifacts."

Note on Coordination: Never omit the comma when connecting two independent clauses ( "The team excavated the citadel and they cataloged artifacts" is a run-on in formal writing).

Method 4: Subordination (Converting to a Complex Sentence)

Demote one of the independent clauses into a dependent clause by attaching an appropriate subordinating conjunction. This method often produces the most sophisticated, nuanced academic prose because it explicitly articulates the logical, causal, or temporal hierarchy between the ideas.

  • "When the archaeological team excavated the ancient citadel, they cataloged hundreds of bronze artifacts."
  • 6. Sentence Repair Decision Matrix

Problem Type Syntactic Structure Flaw Diagnosis Valid Grammatical Solutions

Stranded Subordinate Clause Because the alloy oxidized at high temperatures. Contains subordinator ( Because ), lacks main independent clause. 1. Attach to preceding or following independent clause.; 2. Delete subordinator ( The alloy oxidized at high temperatures. ).

Verbal Fragment The botanists collecting specimen samples across the alpine meadow. Bare participle ( collecting ) without conjugated auxiliary verb. 1. Add finite auxiliary ( The botanists were collecting... ).; 2. Add finite predicate ( The botanists collected... ).

Fused Run-on The turbine failed the rotor bearings seized. Two independent clauses with zero punctuation. 1. The turbine failed. The rotor bearings seized. ; 2. The turbine failed; the rotor bearings seized. ; 3. The turbine failed, for the rotor bearings seized.

Comma Splice The economy expanded rapidly, inflation remained low. Two independent clauses joined solely by a comma. 1. ...expanded rapidly; inflation remained low. ; 2. ...expanded rapidly, but inflation remained low. ; 3. Although the economy expanded rapidly, inflation remained low.

Conjunctive Adverb Splice The glacier receded, consequently lake levels rose. Conjunctive adverb ( consequently ) preceded only by a comma. 1. ...glacier receded; consequently, lake levels rose. ; 2. ...glacier receded. Consequently, lake levels rose.

7. Authentic ACCUPLACER Revision Walkthroughs

Unedited Passage Excerpt Syntactic Diagnosis Edited Academic Revision Grammatical Justification

The marine biologist tagged twelve blue whales, these tracking devices transmitted telemetry data via satellite. Comma Splice: Two independent clauses ( "The marine biologist tagged..." and "these tracking devices transmitted..." ) are improperly connected by a comma alone. The marine biologist tagged twelve blue whales with tracking devices that transmitted telemetry data via satellite. Replaces the comma splice by converting the second clause into a restrictive relative clause ( that transmitted... ), creating a fluid, grammatically unified complex sentence.

Although the composite material resisted tensile stress under laboratory simulation. It degraded rapidly when exposed to ultraviolet radiation. Sentence Fragment: The initial unit is a stranded dependent clause introduced by Although . Although the composite material resisted tensile stress under laboratory simulation, it degraded rapidly when exposed to ultraviolet radiation. Merges the introductory dependent clause with the main independent clause, separated by a comma.

The supercomputer processed three petabytes of climate data in minutes, however, the simulation failed to account for localized ocean currents. Conjunctive Adverb Comma Splice: However is an adverb and cannot join independent clauses with only a comma. The supercomputer processed three petabytes of climate data in minutes; however, the simulation failed to account for localized ocean currents. Replaces the first comma with a semicolon before the conjunctive adverb however , satisfying independent clause boundary rules.