One of the most common errors made by non-native English speakers is having subject(s) and verb(s) that do not agree in number. Here, we discuss some common subject-verb agreement rules.
If the subject is singular, the verb must be singular
If the subject is plural, the verb should also be plural
The GFP method [subject – singular] relies [verb – singular] on cellular transfection …
GFP-based methods [subject – plural] rely [verb – plural] on cellular transfection …
Helping verbs
Have, do and be
A phase 3 trial [subject – singular] is [verb – singular] currently underway.
Two separate phase 3 trials [subject – plural] are [verb – plural] currently underway.
The drug [subject – singular] was [verb – singular] administered by icv injection.
The drugs [subject – plural] were [verb – plural] administered by icv injection.
The last decade [subject – singular] has [verb – singular] seen a growing trend towards …
The last two decades [subject – plural] have [verb – plural] seen a growing trend towards …
However, this result [subject – singular] does [verb – singular] not support previous studies.
However, these results [subject – plural] do [verb – plural] not support previous studies.
Can, could, should, may, might, will, would, and must.
It is now well established that a fracture [subject – singular] can impair …
It is now well established that multiple fractures [subject – plural] can impair …
This discrepancy [subject – singular] could be attributed to …
These discrepancies [subject – plural] could be attributed to …
This result [subject – singular] should be interpreted with caution.
These results [subject – plural] should be interpreted with caution.
A FD-like nuclear protein [subject – singular] may regulate intracellular localization of Hd3a protein in the SAM.
FD-like nuclear proteins [subject – plural] may regulate intracellular localization of Hd3a protein in the SAM.
Diabetes [subject – singular] might be the cause rather than the result of the nervous disturbance.
Diabetes types 1 and 2* [subject – plural] might be the cause rather than the result of the nervous disturbance.
*See below to see why this is considered plural
Often the effect [subject – singular] of heat stress on photosynthesis will be more complex.
Often the combined effects [subject – plural] of heat and light stress on photosynthesis will be more complex.
A simple and eco-friendly synthetic route [subject – singular] would help further promote interest in the synthesis and application of metallic nanoparticles.
Simple and eco-friendly synthetic routes [subject – plural] would help further promote interest in the synthesis and application of metallic nanoparticles.
The wind turbine [subject – singular] must be switched off when the terminal voltage deviates …
Wind turbines [subject – plural] must be switched off when the terminal voltage deviates …
For the past tense, both singular and plural subjects take a verb with an “ed” ending.
A serious adverse event [subject – singular] occurred in one of the patients.
Serious adverse events [subject – plural] occurred in more than one patient.
The sample [subject – singular] consisted of …
The samples [subject – plural] consisted of …
Compound subjects
“Singular subject and singular subject” takes a plural verb.
Glucose [subject – singular] promotes [verb – singular] the development of …
Xylose [subject – singular] promotes [verb – singular] the development of …
Glucose and xylose [singular subject and singular subject] promote [verb – plural] the development of …
“Singular subject or singular subject” takes a singular verb (because there is a choice).
Glucose or xylose [singular subject or singular subject] promotes [verb – singular] the development of …
Compound subjects with different individual parts joined by and take a plural verb.
Laminarin and flagellin peptides [singular subject and plural subject] suppress [verb – plural] photosynthesis-related transcripts.
Flagellin peptides and laminarin [plural subject and singular subject] suppress [verb – plural] photosynthesis-related transcripts.
Compound subjects with different individual parts joined by or/nor take the verb form that agrees with the subject closer to the verb.
X-based methods or the Y method [plural subject or singular subject] provides [verb – singular] a means of …
The Y method or X-based methods [singular subject or plural subject] provide [verb – plural] a means of …
Neither X-based methods nor the Y method [plural subject nor singular subject] is [verb – singular] suitable for testing …
Neither the Y method nor X-based methods [singular subject nor plural subject] are [verb – plural] suitable for testing …
The true subject of a sentence often comes before the word “of”.
The toxicity [subject – singular] of three compounds was [verb – singular] measured …”
Subjects that are measurements/quantities (e.g., Ten millilitres, 5 g) are considered a single entity and so take a singular verb.
Next, 5 g of the powder [subject – singular] was [verb – singular] added to …” = CORRECT
Next, 5 g of the powder [subject – singular] were [verb – singular] added to …” = INCORRECT
Subject-verb agreement with fractions, percentages, and indefinite quantifiers
One-third of this solution [subject – singular] was [verb – singular] poured …
Half of the plates [subject – plural] were [verb – plural] measured …
50% of the treatment group [subject – singular] was [verb – singular] …
50% of the animals [subject – plural] were [verb – plural] …
All the information [subject – singular] is [verb – singular] available …
All the data [subject – plural] are [verb – plural] available …
A phrase or clause serving as the subject takes a singular verb.
Preventing malaria and other tropical diseases from spreading [clause serving as the subject] is [verb – singular] of the upmost importance …
Interpreting these results [clause serving as the subject] was [verb – singular] difficult at first.
In a sentence beginning with the phrase “there is” and “there are”, the verb agrees with the subject that follows.
There are [verb – plural] no figures [subject – plural] available for the animals used here.
There is [verb – singular] one possible explanation [subject – singular] for this.
Example of a well-written scientific paper highlighting subject-verb agreement (PDF, 3MB)
