Editing Tip: Subject-Verb Agreement

In any sentence, the form of a verb must agree in number with the corresponding subject: singular nouns take singular verbs, while plural nouns require plural verbs. A discrepancy in the number of the subject and the verb form can read very awkwardly to native English speakers or even make the meaning unclear, so keep these tips in mind when presenting your material.

“The neural signal were measured with an implanted microelectrode system.” 

Here, the subject (“neural signal”) and verb (“were measured”) are mismatched. To create agreement, we can make either the verb singular (“The neural signal was measured with an implanted microelectrode system”) or the subject plural (“The neural signals were measured with an implanted microelectrode system”). Note that in general, plural nouns are formed by appending an “s” at the end of the word, while plural verbs are not; the opposite construction is also generally applied to the singular forms (i.e., an “s” appears at the end of singular verbs but not singular nouns).

An area where difficulties in subject-verb agreement can be found is when there are words or whole phrases between the subject and verb. When that phrase also contains a noun, it is especially easy to match the grammatical number of the verb to that of the noun in the intervening phrase instead of to that of the subject. For example, “The results of the examination show that the patient had elevated levels of CRP.” Note that the italicized “of the examination” is a phrase that modifies the subject of the sentence, “results”, which is plural and thus requires the plural verb “show”.

Finally, compound subjects are typically treated consistently depending on the coordinating conjunctions used to join them. For example, a compound subject joined by “and” is usually paired with a plural verb (“As shown in the figure, the experimental and control groups do not significantly differ in terms of age or sex ratio.”) If a compound subject is joined by “or” or “nor”, the verb form depends on the numbers of the subject closer to the verb (e.g., “Neither the author nor his colleagues have any conflicts of interest to declare.”)

One exception to the compound subject rule is the use of conjunctions or prepositional phrases such as “with”, “in addition to”, “as well as”, and so forth. In these cases, the phrase does not affect the grammatical number of the subject.

Example: “The percentage of free radicals as well as the site of free radical origin dictates the intervention that should be administered to the patient.” Note that the italicized text is treated as an intervening phrase and that the two nouns “percentage” and “site” are not considered a compound subject; thus, the singular “dictates” is used.

We hope that this editing tip has been helpful as you write your manuscript. Should you have any questions, please feel free to contact us. Thank you, and good luck in your research.