Keep the subject and verb together: the comma rule you should remember

Punctuation, tiny as it is, acts like a traffic signal for sentences. It tells readers when to pause, where to expect a new idea, and how parts of a thought fit together. When you’re looking at the English Accuplacer test, you’ll notice a lot of emphasis on how sentences flow. The good news is that one simple rule can clear up a lot of confusion about commas: a comma never separates a subject from its verb.

Let me explain why that matters and how it shows up in real writing.

The core idea: subject and verb belong together

Think of a sentence’s backbone: the subject tells you who or what the sentence is about, and the verb tells you what that subject is doing. They form a tight pair, a unit that carries the main meaning. If you put a comma between them, you interrupt that core pairing. It’s like pausing right between a dancer and their dance move—odd, and a little disorienting.

Take a simple example: The cat runs quickly. Here, “The cat” is the subject, and “runs” is the verb. They fit together without a hitch. If you wrote The cat, runs quickly, you’d create a moment of pause that doesn’t belong there. It would feel off, as if you accidentally started telling a new thought mid-flow.

That’s why, on the test and in ordinary writing, the subject and its verb stay glued together without a comma. The only time you see a pause between them is when the sentence itself needs permission to take a breath for a bigger reason—like separating two independent ideas with a conjunction, or adding extra information in a nonessential clause. But the basic subject-verb unit stays intact.

A quick tour of where commas actually belong

Before we get too hung up on one rule, here’s a practical map. Commas are useful in several other contexts where they help clarity, rhythm, or emphasis. Here are some common, legitimate uses that you’ll encounter in the test and in everyday writing:

• Between two independent clauses joined by coordinating conjunctions

We went to the library, and we found the perfect reference.

Here the comma before “and” helps signal that two complete thoughts are connected, not tangled.

• After introductory words or phrases

After a long day, I finally sat down to read.

The pause after the opener helps the reader reset before the main idea.

• In a series or list

She bought apples, oranges, bananas, and pears.

The serial comma before the “and” (the Oxford comma) is optional in many styles, but using it can help avoid ambiguity.

• Around nonessential or nonrestrictive information

The car, a bright red coupe, drew everyone’s eyes.

The extra detail sits between commas because it’s not essential to identifying which car is meant.

• With dates, locations, or numbers that benefit from clarity

He was born on May 3, 1994, in Denver, Colorado.

Small pauses here keep the rhythm clear and the meaning precise.

What the test question really drills into

The multiple-choice prompt you cited asks which thing a comma should never separate. The right answer is A: a subject from its object. This distinction matters because the subject and object can be far apart in longer sentences, and the verb often sits in between. But no comma should wedge itself between the subject and the verb that tells us what the subject is doing.

Here are a couple of quick contrasts to cement the idea:

• Correct growth, wrong pause

Correct: The dog runs fast.

Incorrect for this rule: The dog, runs fast.

In the wrong version, the comma makes it look like the subject and its action are two separate thoughts, which muddles meaning.

• When a pause serves a purpose, not a break in the core

Correct: The dog, being a good boy, went home.

Here, the phrase after the subject is a nonessential bit of information, so the commas are allowed—because the structure isn’t just subject-verb anymore; it’s subject, then extra information.

Natural digressions that still lead back to grammar

You might be wondering how often real writers trip over this in the wild. The truth is, even seasoned writers slip when the sentence becomes long and crowded. It’s tempting to sprinkle a comma between a subject and a distant verb, especially when you’re juggling several ideas in one sentence. That moment of hesitation can change the reading pace and make the sentence feel heavier than intended.

A tidy trick is to read the sentence aloud and listen for the “beat.” If the subject and verb want to move together, keep them connected. If you hear a natural hinge or a pause that points to a larger idea, that’s where a comma might belong—but not between the subject and its verb.

Your toolkit for clean sentences

When you’re evaluating a sentence on the test or in any writing task, here are practical moves to keep it readable and correct:

• Identify the core pair first

Locate the subject and the main verb. If pausing between them feels wrong, that’s a sign to keep them together.

• Check the structure around the core

If the sentence has additional phrases, adjectives, or clauses, see where they fit. Nonessential information can be wrapped in commas, but the subject-verb bond stays intact.

• Use commas to slow or cue the reader, not to confuse

A comma should aid clarity, not create an awkward chasm. If inserting a comma would interrupt the natural flow, leave it out.

• Mind the periodic or introductory elements

If you begin a sentence with an introductory phrase like “In the morning,” or “After the meeting,” a comma is often the right move. It sets the stage for the main clause that follows.

• Be mindful of the serial comma

In lists, the presence or absence of the final comma before “and” matters for clarity in some contexts. If you’re unsure, a quick rule of thumb is to include it for readability; many style guides vary, but readers usually benefit from a clear break.

Tiny exercises you can do anywhere

If you want to tune your eye for commas, try a few quick checks on sentences you read in books, emails, or articles:

• Spot the core: Can you point to the subject and the main verb? If yes, you’ll know whether a comma between them is appropriate.

• Test with and without: Read the sentence both ways. Does adding a comma between subject and verb help or hinder clarity?

• Replace a distracting pause: If a sentence feels choppy, experiment with moving or removing commas around introductory phrases or nonessential information. See how the rhythm shifts.

Putting it into everyday language

Grammar isn’t just a dry set of rules. It’s about making meaning clear without forcing the reader to work too hard. When you’re writing about any topic—whether you’re describing a scene, explaining a process, or arguing a point—the goal is to guide the reader smoothly from one idea to the next. The right punctuation does exactly that.

A few conversational notes to round things out

Here’s a small candid truth: English punctuation can feel a bit arbitrary at times. You’ll see moments where a comma seems perfectly reasonable, and then a minute later you’ll encounter the same structure where it would be wrong. The key is to stay flexible but mindful. Don’t fear punctuation; respect its purpose. It’s less about “getting it right every single time” and more about helping readers follow your thinking with ease.

Expect some subtle variations across styles

Different writing communities favor slightly different practices around commas. In journalism, for example, brevity and directness sometimes limit comma usage. In academic writing, the serial comma can be a steadfast companion. In creative prose, punctuation can bend to voice and rhythm. The test will reflect standard English usage, but the underlying aim remains constant: clarity and readability.

Bringing it back to the bigger picture

Even if you’re not chasing a perfect score on a test, paying attention to where a sentence breathes and where it shouts pays off. Strong writing isn’t about cramming punctuation rules into a rigid mold; it’s about shaping your prose so readers feel confident about what you’re saying. The subject-verb bond is a reliable compass in that journey. Keep them linked, and you’ll avoid a common pitfall that trips up many readers.

A final thought—and a tiny invitation

If you’ve ever been puzzled by a sentence and wondered whether a comma belongs there, you’re not alone. English is a living thing, full of little quirks that show up in daily reading and conversation. Use this understanding as a guide, not a cage. The more you notice how sentences move, the better you’ll become at crafting writing that feels natural, confident, and easy to follow.

So, next time you encounter a sentence, ask yourself: where does the main action sit? Is the subject and its verb traveling together, or is there a pause that serves a bigger purpose? Answer honestly, align the pieces, and let the rhythm of your prose carry the meaning forward.

If you’d like, we can walk through more examples or explore how comma usage can subtly change tone—from brisk and direct to warm and reflective. Either way, the core idea remains simple and powerful: keep the subject and its verb close, and let the commas do the guiding where they truly belong.