When two singular subjects are connected by "neither...nor", does it take a singular verb or plural verb? Which is more natural and acceptable?
Neither Mary nor Jane is / are beautiful.
A very clear explanation is here:
When two subjects are joined by neither-nor or either-or, [...] focus your attention on the noun closest to the verb.
If it is singular, as in the sentence above, choose the singular verb. If the noun is plural, choose the plural form of the verb.
So the sentences below are correct:
Neither Mary nor Jane is beautiful.
Neither the boy nor his sisters were wearing seatbelts.
Neither Mary nor Jane is beautiful.
This is the correct sentence. We use singular verb forms after singular nouns and plural verb forms after plural nouns.
Compare:
"Mary" and "Jane" both are single entities so "is" is to be used.