Rules for Subject-Verb Agreement

1. The subject and verb must both exist
2. Subject and verb must make sense together
3. Subject and verb must agree in number; i.e., singular subject requires singular verb form, and plural subject requires a plural verb form
4. Eliminate the middlemen, and skip the warmup; you may eliminate the prepositional phrase and then find if the sentence still makes sense.
5. Use structure to decide. A noun in a prepositional phrase cannot be the subject of the sentence.
6. And Vs Additive phrases. The word and can unite two or more singular subjects, forming a compound plural. These compound subjects take a plural verb form.
7. Or, Either......Or, & neither.....nor. Find the noun nearest to the verb, and make sure that the verb agrees in number with this noun. (when the words either or neither are in a sentence alone, they are considered singular and take only singular verb.
8. Collective nouns: Almost Always take singular verb
9. Indefinite pronouns usually take singular verb. All pronouns that end in -one, -body, or -thing. (Note: Some, Any, None, All, More/Most can be either singular or plural.) None of + plural noun can take either a singular or plural verb form. But not on is always singular:
10. Each and Every: singular sensations.
11. Quantity words and phrases. The number of takes a singular verb, but A number of takes a plural verb.
12. Subject phrases and clauses: always singular