Not always. Sometimes the components of the sentence make it harder to determine agreement.
The first challenge is when an intervening phrase comes between the subject and verb. If the subject is singular, but the intervening phrase is plural, then use a singular verb. Use a plural verb when the subject is plural and the intervening phrase is singular. Always match the verb to the subject. Example: The test on dividing fractions was hard OR Predictions about which horse will win the race are often wrong.
Indefinite pronouns used as the subject can also confuse subject-verb agreement. The table below lists which indefinite pronouns are singular and which are plural.
Collective nouns can also be a challenge. A collective noun names a group. Some common collective nouns are army, audience, council, crowd, and staff. When a collective noun is the subject, it takes a singular verb if the sentence refers to the group as a whole. Example: The staff is located on the third floor.
A collective noun takes a plural verb when referring to individuals members of the group. Example: The staff have decided to paint their offices.
In the past, when the word data was used as a subject, it took a plural verb. However, usage has evolved, and now data is treated as a collective noun. Example: The data is compelling.
Compound subjects can be tricky as well. When subjects (whether singular or plural) are joined by the word and, they take a plural verb, as in "Anna and Lucy are friends." If the subjects are both singular and joined by or or nor, then they take a singular verb, as in “neither the teacher nor the assistant was late.” If one subject is singular and the other plural, then the verb agrees with the subject closest to it. Example: Either the cat or the dogs are responsible for the damage.
Amounts can also trip people up. If the amount is considered one unit, then the verb is singular, as in “two years is a long time to be away.” Otherwise, amounts take plural verbs. Example: “Three days are left in the month.”
Composition titles and the names of countries may complicate subject-verb agreement. Even when the names of works and countries are plural (such as The Final Days or the Netherlands), they take a singular verb because they refer to a single unit. Examples: The Grapes of Wrath is a compelling book AND The United States was represented at the conference.
Although the rules of subject-verb agreement are complex, remember these guidelines, and all your sentences will be in perfect agreement.