Understanding Sentence Structure and Punctuation
In a sense, sentence structure is quite mechanical; in other words, if we can better understand the “parts” of a sentence (rather like the parts in a car engine, for instance), then we can write better sentences. Read the following ideas carefully…then turn around and read them again. Then a third time. The ideas will make more and more sense, and you’ll be able to use them in your writing.
Many sentences are composed of two parts: kernels and phrases. A “kernel” is simply that part of the sentence that’s a complete thought and could, if need be, stand on its own. For instance:
Johnson County is suffering from a reduced tax base.
Now, take a look:
After three years of financial decline, Johnson County is suffering from a reduced tax base.
You’ll see that a phrase—which is an incomplete thought that CANNOT stand alone—is “After three years of solid financial footing” and “Johnson County is suffering from a reduced tax base” is the kernel.
Now…see where the comma goes? Right. After the introductory phrase. We call the phrase “introductory” simply because it starts off the sentence. Do we always place a comma after an introductory phrase? Pretty much…almost always, in fact. Why? Because doing so makes the sentence more readable, and readability is what we want. Now, bear with me while we play around with this sentence:
Johnson County, after three years of financial strain, is suffering from a reduced tax base.
See where the phrase is now? It’s in the middle. Therefore, we simply call it a “middle phrase”. See where the commas are? Right. Before AND after the middle phrase. Always, always, always…no exceptions.
Now, one more time:
Johnson County is suffering from a reduced tax base after three years of financial decline.
What happened to the comma? Did we forget it?
No, we didn’t forget it.
In this version, the sentence does not take a comma. Why? Because this particular phrase is highly “movable”…we can move it around from the beginning to the end. When we have a highly “movable” phrase such as this—typically a prepositional phrase—no comma is used when that movable phrase is at the END of the sentence. Otherwise, the phrase takes one comma as a beginning phrase and two commas as an ending phrase.
Okay, here’s one more syntactic lesson:
Johnson County is suffering from a reduced tax base, a problem that demands innovative fiscal policy and shared sacrifice.
Hey, why the comma this time? Because the ending phrase–“a problem that demands innovative fiscal policy and shared sacrifice”—is NOT highly movable. For instance, you can’t move it to the beginning of the sentence…well, you could, but you’d create a non-grammatical monstrosity. When an ending phrase is “stuck” at the end—when it cannot be moved to the beginning—you typically use a comma between the kernel (the complete thought) and the phrase.
Are there exceptions to these general rules? Yes there are, but the exceptions are rare. Furthermore, thorough understanding of these principles (kernel, phrase, and comma usage) will improve your sentences.
As you work on your essays, make a serious effort to integrate these principles of sentence structure into your work. While the principles themselves are pretty simple, they can pay real dividends…they can, in other words, make immediate contributions to your work.