Subject-Verb Agreement Across Prepositional Phrases

In English, the verb in a sentence must agree with the subject, specifically in terms of number. That is, singular subjects require singular verb forms (e.g., the cat walks), and plural subjects require plural verb forms (e.g., the cats walk). In most cases, writers can easily choose the correct verb form for a subject. However, when other clauses intervene between the subject and the verb, errors in subject-verb agreement become more common. Errors sometimes occur because word processing software does not correctly identify the subject and suggests an incorrect verb form, so be alert as you write any important documents!

In every sentence, it is important to identify the true subject and ensure that the verb agrees in number with that element and not another noun in the sentence. Here are some examples of sentences in which an intervening clause creates some confusion about the proper verb form. In each case, the true subject of the sentence is separated from the verb by a prepositional phrase.

1. The analysis of the results reveals a significant difference between the groups.

• The singular subject 'analysis' requires a singular verb form, 'reveals.'
• Do NOT write: The analysis of the results reveal a significant difference between the groups.

2. The material that was applied to the blades of wind turbines ages rapidly in tests.

• Again, the subject is singular, so the verb must agree with 'material' and not 'turbines.'
• Do NOT write: The material applied to the blades of wind turbines age rapidly in tests.

3. Each of the samples was treated with the same dose of antibiotics.

• Remember that 'each' is a singular subject, and "of the samples" is simply another prepositional phrase.
• Do NOT write: Each of the samples were treated with the same dose of antibiotics (It would be correct to state "All of the samples were treated with the same dose of antibiotics"; 'All' is a plural subject in this case.)

4. The participants who enter the study receive questionnaires.

• In this example, the plural subject 'participants' requires a plural verb form.
• Do NOT write: The participants who enter the study receives questionnaires.

Compound subjects can also create tricky situations. Two nouns or pronouns joined by 'and' create a plural subject and require a plural verb (e.g., "He and I are traveling to Europe" or "The mitochondria and nuclei glow green in this cell line"). However, the subject of a sentence is unaffected when followed by with, together with, along with, as well as, or in addition to. In such cases, the nature of the subject itself determines the form of the verb, not whatever follows the additional term.

The percentage of correct responses as well as the speed of the responses significantly increases with practice.

• The phrase 'as well as' introduces a clause that does not affect the singular nature of the subject ('percentage').
• Do NOT write: The percentage of correct responses as well as the speed of the responses significantly increase with practice.

We hope that this post will be helpful the next time you are deciding whether to use a singular or plural verb. If you have questions about a specific example, contact us at [email protected]. Best of luck with your research and publication!