1. The subject of a sentence or clause must agree in number with the main or auxiliary verb of that sentence or clause.
Ex: The books were on the table yesterday.
Whatever you want to do is fine with me. Every book is checked out.
One of the books was missing. The news is on at 6:00.
2. With fractions, percentages, amounts and distances a singular verb is used when they are not followed by an of phrase.
Ex: $7.50 is the minimum wage.
Five miles is an average distance for me to run.
3. When an –of phrase follows a percentage, distance, fraction, or amount, the verb agrees with the noun closest to the verb.
Ex: Half of the tables are occupied.
21% of the population is poor.
21% of the books are paperback.
4. With indefinite quantifiers (e.g., all, few, many, much, some), the verb agrees with the preceding noun or clause:
With a singular or non-count noun or clause, use a singular verb:
Ex: Much of the book seems relevant to this study.
All the information is current
With a plural noun, use a plural verb:
Ex: Many researchers depend on grants from industry.
All the studies are current.
5. Usually, a singular verb follows NONE, even if the noun following it is plural. However, in conversational English, a plural noun has become acceptable.
Ex: None of the workers receives a tip.
None of the workers receive a tip (less formal).
6. With a collective noun, use either a singular or a plural verb, depending on whether you want to emphasize the single group or its individual members:
Ex: Half of my family lives/live in Canada.
All of the class is/are here.
Ten percent of the population is/are bilingual.
7. Adjectives proceeded by THE and used as plural nouns take a plural verb:
The rich get richer.
The poor face many hardships.
8. Expressions using the phrase number of depend on the meaning of the phrase:
They take a singular verb when referring to a single quantity: The number of students registered in the class is 20.
They take plural verbs when they are used as indefinite quantifiers: A number of students were late.
9. With expressions AS WELL AS, IN ADDITION TO, TOGETHER WITH, the first noun determines if the verb is singular or plural.
Ex: France, as well as other European countries, has a tip-included policy.
Waiters, in addition to others who work for tip, are usually generous tippers.
10. In the subjects with NEITHER/NOR and NOT ONLY BUT ALSO the noun closest to the verb determines if that verb is singular or plural.
Ex: Neither the host nor his guests were happy.
Neither the guests nor their host was happy.
Not only the waiter but also the cook and busboy work for tips.
11. With EITHER/OR, the second noun guests determines that the verb is plural.
Ex: Either John or his brother is going to make dinner.
12. A plural verb is used with subjects using BOTH/AND. However, if the compound subject describes two parts of a single process, then a singular verb is used.
Ex: Both John and his sister are going to be at the party.
Carol and Bob were at the party.
The administration and interpretation of educational tests is an important part of her job.