Identifying and Fixing Sentence Fragments, Run-On Sentences, and Comma Splices

The Anatomy of Sentence Fragments

A sentence fragment is a group of words that is punctuated as if it were a complete sentence (starting with a capital letter and ending with a period, question mark, or exclamation point) but fails to form a complete independent clause. Fragments occur when a word group lacks a grammatical subject, lacks a finite predicate verb, or is an isolated dependent clause.

Four useful fragment patterns to recognize are:

1. Subordinate Clause Fragments

These fragments contain both a subject and a verb, but they begin with a subordinating conjunction (because, although, since, while, if, unless) or relative pronoun (which, that, who). The subordinating word prevents the clause from expressing a complete thought.

• Fragment: "Because the university campus was closed due to severe winter weather."
• Analysis: Contains a subject (campus) and verb (was closed), but the word Because leaves the thought incomplete.
• Correction: Attach to an independent clause: "Because the university campus was closed due to severe winter weather**, classes were held online.**"

2. Participial Phrase Fragments

These fragments center on a present participle (-ing verb form) or past participle (-ed/-en verb form) lacking an auxiliary (helping) verb (is, are, was, were, has been).

• Fragment: "Studying diligently in the science library every evening until midnight."
• Analysis: Studying is a participle, not a finite verb. There is no subject or auxiliary verb.
• Correction (Option A - Add subject & auxiliary): "The students were studying diligently in the science library every evening until midnight."
• Correction (Option B - Attach to main clause): "Studying diligently in the science library every evening until midnight, Chen prepared thoroughly for his chemistry exam."

3. Infinitive Phrase Fragments

These fragments consist of an infinitive phrase (to + base verb) and its modifiers, punctuated as a full sentence.

• Fragment: "To earn an advanced certification in data analytics before graduation."
• Analysis: An infinitive phrase cannot serve as the predicate of a sentence.
• Correction: "Elena registered for weekend workshops to earn an advanced certification in data analytics before graduation."

4. Appositive and Prepositional Chain Fragments

These fragments consist of noun phrases that explain another noun (appositives) or long strings of prepositional phrases without any main verb structure.

• Fragment: "Especially the mandatory orientation modules for international graduate students."
• Analysis: A noun phrase modifying a previous noun, but containing no predicate.
• Correction: "All incoming students must complete the online coursework, especially the mandatory orientation modules for international graduate students."

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Run-On Sentences and Comma Splices: Causes and Diagnostics

While fragments are incomplete sentences, run-on sentences and comma splices occur when independent clauses are combined incorrectly.

Run-On (Fused) Sentences Defined

A run-on or fused sentence occurs when two or more independent clauses are joined with no punctuation and no conjunction between them. The reader is pushed from one complete thought into another without a structural boundary.

• Run-On Example: "The laboratory experiment failed the researchers repeated the procedure."
• Clause 1: The laboratory experiment failed (Independent Clause)
• Clause 2: the researchers repeated the procedure (Independent Clause)

Comma Splices Defined

A comma splice occurs when two independent clauses are joined with only a comma and no coordinating conjunction. In standard written English, a comma alone is not strong enough to join two independent clauses.

• Comma Splice Example: "The laboratory experiment failed**,** the researchers repeated the procedure."

The Conjunctive Adverb Trap

A major trap on the ACCUPLACER ESL exam involves conjunctive adverbs (also called transitional words). Non-native English writers often treat words such as however, therefore, furthermore, nevertheless, moreover, consequently, and meanwhile as coordinating conjunctions.

• INCORRECT (Comma Splice Trap): "The library was closed**, however,** the online database was accessible."
• WHY IT IS WRONG: However is a conjunctive adverb, not a coordinating conjunction (FANBOYS). Placing a comma before however creates a comma splice.
• CORRECT: "The library was closed**; however,** the online database was accessible." (OR: "...was closed**. However,** the online database...")

Four Proven Strategies for Fixing Run-Ons and Comma Splices

When encountering a run-on or comma splice on the ACCUPLACER ESL test, candidates must be prepared to select from four grammatically correct repair strategies:

Diagnostic Method for Spotting Clause Boundary Errors

To quickly diagnose clause errors under exam conditions, apply this step-by-step diagnostic process:

1. Locate all finite verbs in the sentence. (Ignore infinitives like to study and participles like studying unless accompanied by helping verbs).
2. Match each finite verb to its corresponding subject.
3. Count the independent clauses. If there are two independent clauses:
   • Is there a punctuation mark between them? If no, it is a run-on.
   • Is there only a comma between them? If yes (without and, but, so, etc.), it is a comma splice.
   • Is there a comma with a conjunctive adverb like however? If yes, it is a comma splice.