One of the common errors we see in our customers' documents is the misuse of the singular or plural of a verb following or or nor in the subject.
If you wonder about which to use in your writing, this post will help.
Guideline. Use the singular form of the verb when two or more subjects are connected by or--with the following exceptions: (1) when all the subjects are plural; (2) when the subject nearest the verb is plural.
- Either Miriam or Katryn is going to be at the pub tomorrow evening. (The verb is singular because both subjects joined by or--Miriam and Katryn--are singular.)
- Either the band members or the fans are going to lose their hearing at this concert. (The verb is plural because both subjects--members and fans joined by or--are plural.)
- Either Alice Louise or the stage hands are going to stay until the end of the rehearsal. (The verb is plural because stage hands, the subject closer to the verb, is plural.)
- Either the babies or Tali is going to be on the boat this afternoon. (The verb is singular because Tali, the subject closer to the verb, is singular.)
A closer look. When the nouns and pronouns that make up a compound subject represent different persons (first person [I], second person [you], etc.), the form of the verb is governed by the person of the word nearest the verb.
- Either Natalie or I am going to the reunion in PEI. (The choice of am over is is governed by the fact that I [first person: am] is closer to the verb than Natalie [third person: is].)
Guideline. Follow the same guidelines that govern subjects connected by or.
- Neither Miriam nor Katryn has any interest in going to the pub tomorrow evening. (The verb is singular because Miriam and Katryn are both singular.)
- Neither the band members nor the fans are going to lose their hearing at this Theramin concert. (The verb is plural because members and fans are both plural.)
- Neither Alice Louise nor the stage hands are going anywhere near the electrical switches. (The verb is plural because stage hands, a plural noun, is closer to the verb than Alice Louise.)
- Neither the babies nor Tali is going to be outdoors this afternoon. (The verb is singular because Tali, a singular noun, is closer to the verb than babies.)
Source: Grammar for Smart People, by Barry Tarshis.