AnonymousRingo, George or Paul might plays at a wedding

You can only place a bare infinitive after a modal verb. might play, can play, will play, must play, ...

Never an inflected form - these are all wrong: might plays, might played, might playing, ...


CJ

Because modal verbs like "might" (and can, could, may, must) are followed by a bare infinitive (i.e. an infinitive without "to").

"My brother can sing like a bird." (not "sings"). Or: "My brother sings like a bird".
"She must take this medecine twice a day." (not "takes"). Or: "She takes this medicine twice a day."

JK

Sorry, CalifJim was faster than me.

JohnKeatsSorry, CalifJim was faster than me.

Not to worry. It happens all the time here! Anyway, it's good for the OPs to see different ways of saying the same thing.

CJ

CliveHi,The sentence is saying that only one of them might do it. So, a singular subject, a singular verb.Clive

What do you mean, Clive?
JK

CliveHi,I didn't really pay attention to the fact that it was a modal + bare infinitive. I suppose I should have.I focused on the fact that A, B or C suggests a singular subject.eg A, B and C play the drums.eg A, B or C plays the drums.Clive

So, the verb after modals do not take the 3rd person singular "s"?

AnonymousSo, the verb after modals does not take the 3rd person singular "s"?

That is correct.