It’s interesting, as Margaret Brenner of Towson University points out, that in the present tense, nouns and verbs form plurals in opposite ways: nouns ADD an “s” to the singular form, while verbs REMOVE the “s” from the singular form.
- The technician conducts tests.
- Technicians conduct tests.
The overriding rule to remember is this: The subject and verb of a sentence must agree in number. Either both are singular or both are plural.
- The results were misleading, and it was discovered the system was at fault.
When noun phrases are joined by “and,” the verb must be plural:
- Technicians’ health and safety were at risk.
- The equipment, the reagents, and the room temperature were all at fault.
When the sentence contains alternative subjects (joined by “or,” “either…or,” “neither…nor,” or “not only…but also”), the verb must agree with the last subject:
- Not only the reagents, but the instrument was at fault.
- Either the instrument or the reagents were at fault.
- Not only the instrument, but the reagents were at fault.
A collective noun (referring to a group of people or things) may take either a singular or a plural verb. (Authors may decide whether to consider individual members within the unit or the unit as a whole, and the writing should be consistent throughout the paper.)
- A variety of dosages were tried. Or…A variety of dosages was tried.
- The group was pleased with the results of the experiment. Or…The group were pleased with the results.
See our post on collective nouns for a more in-depth discussion of this topic.
When a phrase comes between a subject and its verb (whether set off by commas or not), the subject and verb must still agree in number, without regard for what comes between.
- The format of the experiment (across laboratories and replicates) was altered.
- The test tube tray, including most of the tubes themselves, was damaged by construction workers entering the lab.
A subject with an indefinite number, where a parenthetical (s) is added to the noun, takes a singular verb.
- The procedure(s) is considered routine in most laboratory protocols.
- What journal(s) in the field of molecular biology has the highest impact factor now?
In some cases, such as sentences with long or complex noun phrases, it can be challenging to determine whether a subject is singular or plural. However complex the writing, however, rules are rules—subjects and verbs cannot be allowed to disagree!