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5.1 Sentence Fragments, Run-Ons, and Comma Splices

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ACCUPLACER Writing Study Guide Exam

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1 Introduction & ACCUPLACER Writing Overview

1.1 About the ACCUPLACER Writing Test 1.2 Test-Taking Strategies & Passage-Based Revision

2 Expression of Ideas: Development

2.1 Proposition, Thesis Statements, and Topic Sentences 2.2 Supporting Details, Evidence, and Textual Relevance 2.3 Audience, Rhetorical Purpose, and Essay Focus

3 Expression of Ideas: Organization

3.1 Logical Sentence and Paragraph Sequence 3.2 Transitional Words and Cohesive Devices 3.3 Effective Introductions, Conclusions, and Summary Sentences

4 Expression of Ideas: Effective Language Use

4.1 Precision and Contextual Vocabulary 4.2 Concision and Eliminating Redundancy 4.3 Style, Tone, and Formal Academic Diction 4.4 Sentence Combination, Syntactic Variety, and Structure

5 Standard English Conventions: Sentence Structure

5.1 Sentence Fragments, Run-Ons, and Comma Splices 5.2 Parallel Structure in Lists and Compound Elements 5.3 Misplaced, Dangling, and Illogical Modifiers 5.4 Subordination, Coordination, and Clause Relationships

6 Standard English Conventions: Conventions of Usage

6.1 Subject-Verb Agreement 6.2 Pronoun Agreement, Antecedent Clarity, and Pronoun Case 6.3 Verb Tense, Sequence, and Aspect 6.4 Frequently Confused Words and Idiomatic Prepositions

7 Standard English Conventions: Conventions of Punctuation

7.1 End-of-Sentence Punctuation and Comma Rules 7.2 Semicolons, Colons, and Dashes 7.3 Apostrophes, Possessives, and Quotation Marks

5.1 Sentence Fragments, Run-Ons, and Comma Splices

Key Takeaways Explain This Topic AI

A complete sentence must contain at least one independent clause, meaning it has a subject, a working verb, and expresses a complete thought.

Sentence fragments are often disguised as long dependent clauses or phrases that lack a main verb.

A run-on sentence occurs when two independent clauses are joined without proper punctuation or conjunctions.

Comma splices, a specific type of run-on, incorrectly join two independent clauses with only a comma.

Fix run-ons by using a period, a semicolon, a comma with a coordinating conjunction, or by subordinating one of the clauses.

Last updated: July 2026

Introduction to Sentence Boundaries

One of the most heavily tested areas on the ACCUPLACER Writing test is the ability to recognize and correct sentence boundary errors. To succeed, you must be able to confidently identify where one sentence should end and another should begin. This requires a deep understanding of clauses, which are the building blocks of sentences.

The Anatomy of a Sentence

At its core, a complete sentence requires three essential elements:

A Subject: The noun or pronoun performing the action.

A Verb: The action or state of being (this must be a working verb, not an -ing participle acting alone or an infinitive).

A Complete Thought: The clause must be able to stand alone logically without leaving the reader hanging.

Together, these three elements form an independent clause . Every grammatical sentence in the English language must contain at least one independent clause.

Clause Identification Chart

To help you distinguish between the types of clauses and phrases, study the chart below:

Structure Type Contains Subject? Contains Verb? Expresses Complete Thought? Can Stand Alone?

  • Independent Clause Yes Yes Yes Yes
  • Dependent Clause Yes Yes No No
  • Prepositional Phrase No No No No
  • Participial Phrase No Yes (Non-working) No No
  • Sentence Fragments

A sentence fragment is an incomplete sentence masquerading as a complete one. It is punctuated with a capital letter at the beginning and an end mark at the close, but it fails to meet one of the three core requirements of an independent clause.

On the ACCUPLACER, fragments are rarely as simple as "The dog." Instead, the test-makers disguise them by making them extremely long. They often use dependent clauses or long phrases to trick your ear into thinking the sentence is complete just because it contains many words.

Common Fragment Traps

Trap 1: The Dependent Clause Fragment Dependent clauses begin with subordinating conjunctions (like although, because, since, while ). When a sentence starts with one of these words, it cannot end until an independent clause is attached.

Incorrect (Fragment): Although the scientists worked for decades to develop the new vaccine for the highly contagious virus.

Why it's wrong: It has a subject ("scientists") and a verb ("worked"), but the word "Although" makes it a dependent clause. It does not express a complete thought.

Correction: Although the scientists worked for decades to develop the new vaccine for the highly contagious virus, they did not receive public recognition until last year.

Trap 2: The Participial Phrase Fragment Present participles (words ending in -ing) and past participles (words often ending in -ed or -en) cannot serve as the main verb of a sentence unless they are paired with a helping verb (like is, was, have, had ).

Incorrect (Fragment): The committee meeting for over three hours to discuss the newly proposed budget cuts affecting the arts programs.

Why it's wrong: "Meeting" is a participle, not a working verb. There is no independent clause.

Correction: The committee met for over three hours to discuss the newly proposed budget cuts affecting the arts programs.

Run-Ons and Comma Splices

If fragments are sentences that are missing crucial pieces, run-ons are sentences that have too many independent clauses jammed together improperly.

A run-on sentence (specifically, a fused sentence) occurs when two independent clauses are smashed together with absolutely no punctuation between them.

Example: The weather was beautiful we decided to go for a hike.

A comma splice is the most common type of run-on tested on the ACCUPLACER. It occurs when a writer attempts to join two independent clauses using only a comma.

Example: The weather was beautiful, we decided to go for a hike.

STUDENT TRAP: Many students mistakenly believe that a run-on is just a sentence that is "too long." Sentence length has absolutely nothing to do with grammatical correctness. A sentence can be 100 words long and perfectly correct, or it can be five words long and be a run-on.

Run-on: I ran she walked.

Correct: Even though the storm raged for days, causing massive power outages across the eastern seaboard and forcing thousands of residents to seek shelter in temporary facilities, the emergency response teams managed to maintain order and provide necessary supplies to those in need.

Four Ways to Fix a Run-On or Comma Splice

When you identify two independent clauses that need to be joined, you have four primary tools at your disposal:

1. The Period ( . ) The simplest fix is to separate the independent clauses into two distinct sentences.

Comma Splice: The museum exhibition opens tomorrow, the curators are working late to finish the displays.

Fix: The museum exhibition opens tomorrow. The curators are working late to finish the displays.

2. The Semicolon ( ; ) A semicolon is grammatically identical to a period. It separates two independent clauses. Use it when the two thoughts are closely related.

Fix: The museum exhibition opens tomorrow; the curators are working late to finish the displays.

3. Comma + Coordinating Conjunction ( , + FANBOYS ) You can join two independent clauses by using a comma followed by one of the FANBOYS (For, And, Nor, But, Or, Yet, So).

Fix: The museum exhibition opens tomorrow, so the curators are working late to finish the displays.

Note: You must have BOTH the comma and the conjunction. A comma alone is a comma splice. A conjunction alone without a comma is also technically incorrect when joining two full independent clauses.

4. Subordination You can fix a run-on by turning one of the independent clauses into a dependent clause. This often improves the flow and clarifies the relationship between the ideas.

Fix: Because the museum exhibition opens tomorrow, the curators are working late to finish the displays.

Passage-Based Editing Breakdown

Let's examine how this might look in an ACCUPLACER-style passage.

Original Text: (1) The architect designed the skyscraper to withstand high winds, he incorporated a tuned mass damper near the roof. (2) A massive block of concrete that sways in the opposite direction of the building. (3) This technology significantly reduces the structural stress during storms.

Analysis & Correction:

Sentence 1 is a classic comma splice. "The architect designed the skyscraper to withstand high winds" is an independent clause. "He incorporated a tuned mass damper near the roof" is also an independent clause. The comma between "winds" and "he" is illegal. We can fix this by changing the comma to a period, changing the comma to a semicolon, or adding a conjunction like "and" after the comma.

Sentence 2 is a sentence fragment. "A massive block of concrete that sways in the opposite direction of the building." It lacks a main, working verb. "That sways" is part of a relative clause modifying "block." We can fix this by attaching it to Sentence 1 (e.g., "...near the roof, a massive block of concrete that sways...") or by adding a verb (e.g., "It is a massive block...").

Sentence 3 is a complete, correct sentence.

Summary of Strategies

When facing sentence boundary questions, always isolate the clauses. Find the subject and the verb. If a clause can stand on its own, it is independent. Never join two independent clauses with just a comma. Watch out for dependent markers (like although, since, because ) that turn independent clauses into fragments if not properly connected to a main clause.