Subject verb agreement has many rules. Singular subjects take singular verbs and plural subjects take plural verbs. Two subjects joined by "and" usually take a plural verb, unless they refer to the same thing. Subjects beginning with each, every, no one, etc. take singular verbs, while subjects beginning with some, many, few, both, etc. take plural verbs. The verb agrees with the closer subject in "either/or" constructions. Single gerunds and collective nouns usually take singular verbs.