7.1 End-of-Sentence Punctuation and Comma Rules

End-of-Sentence Punctuation

Every complete sentence must end with appropriate terminal punctuation. The English language uses three primary marks to end a sentence: the period, the question mark, and the exclamation point. While this might seem elementary, the ACCUPLACER exam frequently tests your ability to choose the correct punctuation based on the context and tone of the sentence.

The Period

The period is the most common terminal punctuation mark. It is used to end declarative sentences (statements of fact or opinion) and imperative sentences (commands or requests). When you state a fact or give a command without strong emotion, a period is the correct choice.

Examples:

• Declarative: The research team discovered a new species of frog in the Amazon rainforest.
• Imperative: Please submit your completed application by Friday.

Student Trap: A common mistake is using a comma where a period is required, leading to a comma splice. Always ensure that independent clauses are properly separated.

The Question Mark

Question marks are used to end direct questions. If a sentence asks something and expects an answer, it must end with a question mark.

Examples:

• What time does the seminar begin?
• Have you finished reviewing the quarterly report?

Student Trap: Do not use a question mark for an indirect question. Indirect questions are statements about questions and should end with a period.

• Incorrect: He asked if I was going to the meeting?
• Correct: He asked if I was going to the meeting.

The Exclamation Point

Exclamation points are used to express strong emotion, surprise, or urgency. They should be used sparingly in formal academic or professional writing. Overusing exclamation points can make your writing seem unprofessional or overly dramatic.

Examples:

• Watch out for that falling rock!
• I can't believe we won the championship!

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Comma Rules and Usage

The comma is arguably the most versatile and frequently misused punctuation mark in the English language. Commas tell the reader to pause, helping to clarify the meaning of a sentence by separating its parts. The ACCUPLACER exam heavily tests your understanding of comma rules.

1. Items in a Series

Use commas to separate three or more items in a list or series. The final comma before the coordinating conjunction (usually "and" or "or") is known as the Oxford comma or serial comma. While some style guides make it optional, using it generally prevents ambiguity, and on standardized tests, it is often preferred or required for clarity.

Example: The recipe calls for flour, sugar, eggs, and milk.

2. Independent Clauses

An independent clause is a group of words that contains a subject and a verb and can stand alone as a complete sentence. When you join two independent clauses with a coordinating conjunction (for, and, nor, but, or, yet, so—often remembered by the acronym FANBOYS), you must place a comma before the conjunction.

Example: The sun was setting over the mountains, and the valley was plunged into darkness.

Student Trap: Do not use a comma when the conjunction joins a compound predicate (two verbs sharing the same subject).

• Incorrect: She finished her homework, and went to bed.
• Correct: She finished her homework and went to bed.

3. Introductory Elements

Use a comma after introductory phrases, clauses, or words that come before the main clause. This signals to the reader that the main subject and verb of the sentence are about to begin.

Examples:

• Introductory word: However, the results were inconclusive.
• Introductory phrase: In the middle of the night, a loud noise woke everyone up.
• Introductory clause: Because the weather was severe, the flight was canceled.

4. Essential vs. Nonessential Clauses

This is one of the most critical concepts tested on the ACCUPLACER. A nonessential (or nonrestrictive) clause adds extra information to a sentence but can be removed without changing the basic meaning of the sentence. Nonessential clauses must be set off by commas. An essential (or restrictive) clause contains information that is necessary to identify the noun it modifies. Essential clauses are NOT set off by commas.

In the essential example, the clause "who studies consistently" specifies which student we are talking about. In the nonessential example, we already know we are talking about John, so the clause just adds extra detail.

5. Coordinate Adjectives

Use a comma to separate two or more coordinate adjectives that modify the same noun. Coordinate adjectives are equal in importance. You can test if adjectives are coordinate by seeing if you can place "and" between them or reverse their order without changing the meaning.

Example: The cold, harsh wind blew across the plains. (You could say "cold and harsh" or "harsh, cold wind," so the comma is correct.)

6. Appositives

An appositive is a noun or noun phrase that renames or identifies another noun right next to it. Like nonessential clauses, nonessential appositives are set off by commas.

Example: My best friend, a talented musician, is releasing a new album.

Common Comma Errors to Avoid

Comma Splices: A comma splice occurs when two independent clauses are joined solely by a comma, without a coordinating conjunction. This is a major grammatical error.

• Incorrect: The movie was excellent, we watched it twice.
• Correct: The movie was excellent, and we watched it twice.
• Correct: The movie was excellent; we watched it twice.

Separating Subject and Verb: Do not place a single comma between a subject and its verb, even if the subject is long or complex.

• Incorrect: The intricate details of the grand architecture, left the tourists in awe.
• Correct: The intricate details of the grand architecture left the tourists in awe.

Passage-Based Editing Example: Original text: The committee members having reviewed all the proposals, decided to fund the renewable energy initiative. Correction: The phrase "having reviewed all the proposals" is a nonessential participial phrase modifying "committee members." It must be enclosed in commas. The correct version is: "The committee members, having reviewed all the proposals, decided to fund the renewable energy initiative."

Understanding these comma rules will significantly improve your ability to identify and correct punctuation errors on the exam. Practice distinguishing between essential and nonessential information, and always be on the lookout for comma splices and missing commas after introductory elements.