either.. or, neither .. nor

If the number is different, the number of the subject nearer to the verb determines whether singular or plural form should be used

frightened vs afraid

frightened by
afraid of

Admission vs Admittance

Admission - entry along with rights and privileges

Admittance - physical entry

Posessive form of ancient classical names

Possessive form of ancient classical names include a ' at the end of the word

Moses' leadership
Jesus' sermon
Achilles' heel

About vs Around

about - approximately
around - refers to motion

GMAT Grammar rule

When two distinct words or phrases are joined by

either . . . or
neither . . . nor
not only . . . but also

number (singular or plural) of the word or phrase nearer to the verb determines the number of the verb.

GMAT Grammar rule

Joining a singular subject with other noun(s) or pronoun(s), by prepositions such as along with, together with, with, as well as, in addition to, or accompanied by does not make the singular subject plural
Only "and" can join two singular subjects and make them plural