Now that we all understand the grave importance of using a comma and a conjunction to join two independent clauses (right? RIGHT?), we can start looking at some of the other, wackier, pain-in-the-assier comma rules that writers tend to flub. And remember, I’m talking rules here, honest-to-goodness rules, which you are free to break because you are a Writer, but please, please, learn them first. Break them later. Your readers will thank you.
For today, let’s take a simple one: A compound sentence requires a comma, whereas a compound predicate does not.
Half of you just stopped reading, including my father, who told me last time I wrote one of these grammar posts that he gave up on it as soon as he got to the word “gerund.” Hi, Dad! Stick around! This time, it’ll be fun. Pinky swear.
Now, we’ve already talked about compound sentences, but maybe you don’t remember. <– See that? That’s a compound sentence right there. (Ooh. Tricky!)
A compound sentence is simply a sentence with two or more independent clauses.
We talked about independent clauses a lot last time: subject/verb combinations that can stand alone as sentences. Feel free to read Commas for Writers, Take One again if you need a refresher course. We’ll wait.
So. Okay. “Sean smiled” is not a compound sentence. It is a simple sentence. So is “Sean smiled at Katie.” But “Sean smiled at Katie, and then he leaned down and kissed her until she started breathing funny” is a compound sentence, because it has those two independent clauses: “Sean smiled at Katie” and “Then he leaned down and kissed her until she started breathing funny.”
In a compound sentence, as we have discussed, you gotta gotta gotta have that comma and conjunction between the two clauses.
A compound predicate, on the other hand, is where the same subject/noun governs two verbs.
- Sean smiled and laughed.
- The leaf whirled and twirled on its way to the ground.
- Ruthie ranted and raved about grammar until everyone got bored.
In each of those sentences, I’ve got one subject (Sean, the leaf, Ruthie) and two verbs (smiled and laughed, whirled and twirled, ranted and raved). Thus, each sentence has a simple subject and a compound predicate.
Seems easy, right? A no-brainer? Let’s look at our original example again and contrast it to one with a compound predicate:
- Sean smiled at Katie, and then he leaned down and kissed her until she started breathing funny. This one, as we’ve already seen, needs that comma in the middle.
- Sean smiled at Katie and tickled her ribs until she started breathing funny. This one does not require a comma, because “Sean” is the subject of the whole sentence (Sean smiled … and tickled).
It is simple! Yay!
And the good news is, these two types of sentences are everywhere. They made up, like, twenty sentences of the 1,800 words I wrote this morning. Here are a few:
- Sean pulled the gun out of the holster at his hip and placed it on the glass-topped table by a bowl of green apples, where it looked bizarrely correct. Compound predicate (Sean pulled … and placed)
- He lifted the tight, stretchy red shirt shed worn under her jacket and put his nose in her navel, breathing in the lemony smell of her skin. Compound predicate (He lifted … and put)
- Sean tried to move his hands up her back, but the holster got in the way. Compound sentence (Sean tried / holster got)
- Her hair was damp at the temples, and her skin glowed in the soft city light that filtered through the glass wall of the hotel room. Compound sentence (Hair was / skin glowed)
If you can recognize the difference between a compound sentence and a compound predicate, correctly punctuating each, you will be one step ahead of all the other chumps in the Grammar Olympics.