Rule of Thumb:
When a compound subject contains two singular nouns separated by the words “or” or “nor,” use a singular verb.
Either Well A or Well B is next on the list to be drilled by the Bandersnatch #6 rig.
Neither Well C nor Well D has been hooked up yet.
But what about the case where one of the nouns is singular and one of the nouns is plural? “That depends.” (This is the Standard Engineer’s Answer.) That depends on which one is closest to the verb.
Either the beam pump or the two ESPs are to be installed this week.
Either the two ESPs or the beam pump is to be installed this week.
This brings us to the sentence I ran across recently.
If one or more (is or are) outside the specifications, the lot will be refused.
Which subject is closest to the verb? “More.”
Is that singular or plural? Plural, as it refers to more than one.
Which is the plural verb form? “Are.”
If one or more are outside the specifications, the lot will be refused.
Famous Quote of the Day:
“You can discover more about a person in an hour of play than in a year of conversation.”
– Plato, Greek philosopher, 427-347 BC