I was tasked to write about a grammar issue for a coming book using zombies to explore prose issues. So I chose Subject-verb agreement.
Subjects and verbs “agree” when they are both singular (one zombie growls), or both plural (two zombies growl).
Native speakers usually make the right choice automatically—that is, in normal simple sentences. The problem usually comes when there’s some distance between the subject and the verb, so you’ve kind of forgotten what “number” the subject is. Here’s an example:
Giles, in his treatises on the varieties of the undead, define zombies as the undead ones who lack brainpower and eat brains. THIS IS WRONG—SINGULAR SUBJECT (TRETORN), BUT A PLURAL VERB (DEFINE).
Why do we make that mistake? That’s because we’ve lost sight of what the true subject is because of the other nouns in between—treatises, varieties, undead—which are all plural. But who is doing the defining? Giles. And there’s only one Giles, so that’s singular, and should take a singular verb:
Giles, in his treatises on the varieties of the undead, defines zombies as the undead ones who lack brainpower and eat brains. THIS IS RIGHT—SINGULAR SUBJECT, SINGULAR VERB.
Another situation that commonly causes this mistake is when the subject is echoed by the pronouns “who or which”, both of which in their disconnected state lack number. (How many “who’s” are there?) Who and which take on the “number” (that is, singular or plural) of the noun they replace.
In the undead hierarchy, zombies have a low status compared to the vampires, who is/are? usually elegant, intelligent blood-drinkers.
That should be “are”-- “who” replaces the plural noun “vampires.”
In the undead hierarchy, zombies have a low status compared to the vampires, who are usually elegant, intelligent blood-drinkers.
Notice—just to complicate things further—this rule applies even when the noun isn’t the subject of the whole sentence. Here, “vampires” is just the subject of the “who are elegant, intelligent blood-drinkers.”
Looking for more complication? Okay! What if you have two subjects, one singular and one plural? Ready? (This is REALLY complicated.)
The zombie and the two vampires has/have been fighting over the frightened accountant.
In this case, it’s easy enough with that “and”—there are three undead ones, and they’re all fighting, so “three are”. With multiple subjects joined by “and”, you just add them up. More than one? Plural, so plural verb—are fighting.
The zombie and the two vampires have been fighting over the frightened accountant.
But… but… what if the subjects are joined by “or”?
Soon, either the zombie or the vampires is/are going to notice that their prey has fainted dead away.
Addition doesn’t work here! In the end, either one or two will notice! What now? Weirdly, it depends on which of the two subjects is closest to the verb. (Really. It’s a sound thing.) So:
Soon, either the vampires or the zombie is going to notice soon that their prey has fainted dead away.
Soon, either the zombie or the vampires are going to notice soon that their prey has fainted dead away.
A Pondian Thing:
One more complication! This is a geographic difference—“a Pondian distinction,” as the linguists say (Pond = the Atlantic Ocean).
In British English, collective (group) nouns like “horde” and “coven” are plural. So you’d say:
The coven were meeting at the haunted grove.
But in American English, collective nouns are usually singular, so:
The coven was meeting at the haunted grove.
However… in American English, a collective is singular only when it’s “one”—all unified in this action, as the coven was in its meeting.
But a collective is plural when it is divided or in disagreement, like: The zombie horde were running around in all directions like zombie chickens.
As usual with English issues, there is a fairly simple rule, but there are also variations depending on usage.
Just to summarize:
General rule: If the subject/noun is singular, its verb should also be singular. One zombie->eats a brain.
But if the subject/noun is plural, then its verb should also be plural. Three zombies->fight over the scraps.
Joined by “and”, the subjects are plural and take the plural verb. The witch, the vampire, and the zombie->walk into a bar.
Joined by “or”, the nearest subject to the verb determines the number:
The devil or maybe two of his demons àhave delivered this contract for your soul.
Either the angels or the lamb being led to slaughter-> is responsible for those tufts of white puff along the path.