Understanding parallel structure and why 'his diaper has been changed' is the best fit for a bedtime sentence.

A calm bedtime scene can teach you more about writing than you might expect. If you’ve ever watched a parent get a baby to sleep, you know that a single sentence can carry more than one message at once: safety, routine, and reassurance. The same idea shows up in the PACT Writing Test (the test focuses on clarity, coherence, and correct grammar), where keeping your sentences in the same rhythm makes your ideas land smoothly. Let me explain with a small, everyday example that helps illustrate parallel structure.

Why parallel structure matters (in plain language)

Parallel structure means the parts of a sentence that are related should look the same grammatically. Think of it as keeping the same cadence when you list actions, describe a sequence, or connect ideas. When the forms line up—tense, voice, and structure—readers don’t have to pause to reinterpret what you’re saying. They flow from one thought to the next, almost without effort. And in the realm of writing for school, work, or daily communication, that flow is what keeps your message clear and credible.

Now, onto the little bedtime sentence that trips people up—and why one option works best

A quick example with a baby

Question: What completion correctly follows the parallel structure regarding the baby being ready for bed?

Options:

A. I have changed his diaper

B. his diaper had been changed

C. his diaper has been changed

D. his diaper was changed

Answer: D, or, more precisely in this context, the option that keeps the idea in a matching frame is “his diaper has been changed.” If you’re describing a sequence that ends with the baby being ready for bed, you want a completion that sits neatly in the same time frame you’re using to describe readiness. You’re not simply noting a past event; you’re marking a condition that holds as part of the present moment. In other words, the diapers is changed, and that matters right now because bedtime has arrived.

Why option D fits the bill

• Present perfect vs. simple past: “has been changed” signals a past action with present relevance. The moment you say the diaper has been changed, you’re also signaling that the state is current and true now—perfect for stating a condition that influences the next step (getting ready for bed).

• Parallel rhythm: if you’ve already described a set of actions in a similar time frame (for example, “the baby is fed, the room is quiet, the diaper has been changed”), then finishing with a present-perfect clause keeps the same tense and cadence. It’s like keeping the same beat in a song—the lines don’t stumble.

• Avoiding mismatch: options A, B, and D disrupt the rhythm for different reasons. “I have changed his diaper” switches the subject from the baby to the speaker; unless your sentence is specifically about the speaker, it sounds off in a routine description. “his diaper had been changed” flips to the past perfect, which can feel tucked away from the present moment. “his diaper was changed” is simple past and feels like a completed, isolated action—less connected to the current state of readiness.

A quick detour that clarifies how this applies more broadly

You’ll see parallel structure pop up in emails, memos, and short essays, not just grammar drills. For instance, imagine you’re outlining a short description of a daily routine: “He brushes his teeth, he washes his hands, he puts on pajamas.” If you switch one item to a different form, like “He brushed his teeth” or “He has washed his hands,” the rhythm breaks and the flow feels lumpy. You’ll notice your reader has to pause, and that pause can dilute the message. Keeping the verbs in the same form keeps the momentum, which matters whether you’re writing for a class, a tutor, or a colleague.

A friendly guide to spotting parallel structure (and fixing it fast)

• Scan for lists or sequences: Are all the items in the same tense and shape? If not, tweak the verbs to match (for example, all present perfect or all simple past).

• Watch the subject: If you’re talking about the same subject across clauses, keep the same person and voice. Switching from first person to third person midstream can create a stumble.

• Use signals to tie ideas together: Transitional words like “and,” “then,” or “as soon as” help maintain rhythm when you’re adding steps.

• Favor consistency in forms: If you start with a noun phrase, keep it that way. If you begin with a verb phrase, end with a verb phrase.

From theory to everyday writing

Parallel structure isn’t a dusty grammar rule locked away in a dusty workbook. It’s a living craft that shows up in emails to professors, notes to teammates, social updates, and, yes, bedtime descriptions. When your writing keeps a steady shape, readers trust what you’re saying more quickly. They don’t get distracted by awkward jumps between tenses or mismatched phrases. And that trust is what turns a good sentence into a convincing one.

A few practical tips you’ll actually use

• Start with a quick check: If you have a list of actions, ask, “Are all items in the same tense and form?” If not, adjust. Simple fix, big payoff.

• When describing a sequence, pick a tense and hold it. If one clause must be in a different tense because it represents a separate time frame, set it off clearly so your reader can follow the shift.

• Read your sentence aloud. If it sounds off, it probably is. Rhythm is a good indicator of structure.

Three bite-sized prompts you can try right now

These aren’t exam drills; they’re everyday checks you can drop into your writing life.

• Prompt 1: Describe a morning routine in one sentence using parallel structure for three actions (e.g., “She brushes her teeth, she washes her face, she ties her hair.”).

• Prompt 2: Write two sentences about a small achievement you’re proud of, each using the same tense and voice.

• Prompt 3: Take a short paragraph about a late-night project and scan for any verb forms that don’t match the rest of the paragraph. Replace one or two to restore rhythm.

A little broader perspective

Why bother with this level of precision? Because language lives in tiny choices. A single tense shift or a mismatched form can create a subtle barrier. Your reader might pause, re-parse, and lose the thread of your point. When you aim for clean, balanced sentences, you free your ideas to speak clearly. It’s a bit like laying out the pieces of a puzzle so the picture comes together without forcing the viewer to hunt for the corners.

A few words about tone and flexibility

The best writing lives in a sweet spot between polish and natural speech. In professional settings, you’ll lean on accuracy and conciseness, but you can still carry warmth and personality. For general writing, you can let a sentence breathe a little more—without losing the structure that keeps it readable. If you’re ever unsure, read your draft aloud. If you stumble, rework that segment until the rhythm feels right.

A memorable takeaway

Parallel structure is the backbone of readable, credible writing. It keeps ideas aligned, helps readers follow your logic, and quietly conveys a sense of control. In contexts like the PACT Writing Test, it’s not about clever tricks; it’s about clarity, consistency, and tone. The example with the baby’s diaper isn’t just about a single right answer. It’s a tiny model for how to keep your sentences in sync, so your message lands with confidence.

To close with a gentle nudge

When you notice a sentence that feels off, don’t worry—you’re not alone. A little adjustment is often all that’s needed: a single verb change, a shift in tense, or a simple reordering of clauses. And if you ever feel stuck, go back to the core idea you want to convey, then rebuild the sentence to echo that idea in a steady, familiar rhythm. Writing should feel like talking with a friend who’s listening closely—clear, steady, and a bit warm.

If you’re curious about how these ideas show up in real-world writing, try spotting parallel structure in everyday content: a blog post, a company update, or even a quick text. The more you notice it, the more natural it becomes to apply. And as you grow more confident, you’ll find your own flow—the kind that makes even a simple sentence about bedtime feel precise, relaxed, and unmistakably yours.