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When one action occurred before another, the past perfect tense can be used to indicate the earlier action, with the
subsequent action in the simple past tense. The past perfect tense is formed by combining the word ‘had’ with the past
participle (typically the ‘-ed’ or ‘-en’ form) of a verb. Examples combining the past and past perfect tenses include “the
cells that had been irradiated [past perfect] were assayed [past] for DNA damage” and “patients who had elected [past
perfect] to undergo surgery completed [past] questionnaires.” In rare cases in which one action occurred while
another was ongoing, the past progressive is used (e.g., “while the cells were incubating [past progressive], the
temperature was raised [past] 1°C per hour” or “while patients were preparing [past progressive] for surgery, nurses
collected [past] baseline samples”). The past progressive is a combination of the verb ‘was’ or ‘were’ and the present
participle (‘-ing’ form) of the verb.
Results: Because the experiments described in the text were completed before the paper was written,
the results section of a manuscript is also largely written using the past tense (for example, “we detected
no fluorescence in the control sample” or “all participants reported a significant reduction in pain”). In
certain cases, however, the present tense is needed. As described above for the introduction section, the
present tense is appropriate when referring to the entire paper or to individual elements of the manuscript (e.g., figures,
tables, sections, results, or data). Examples of statements for which the present tense is best include “our results
demonstrate that magnesium is essential for enzymatic function,” “Figure 1 shows our fluorescence data,” and “in this
study, we report the discovery of a new species of frog.” Note that sometimes two tenses can be found within the same
sentence: “because no enzymatic activity was detected [past tense] in the absence of magnesium, our results indicate
[present tense] that magnesium is [present tense] absolutely required.” The present tense is appropriate for the last
verb because the observation extends beyond the specific experiment referenced in the first part of the sentence; it is
now considered a statement of fact based on the results.
Discussion: The discussion section follows the same rules as the previous sections of the manuscript.
When referring to specific results or methods, use the past tense, but use the present when presenting
conclusions (“we conclude that gene X is dispensable for ornithine synthesis”). However, the discussion
may include the future tense if directions for additional research or scholarship are brought up (e.g., “the
methods reported here will allow for rapid screening in the field” or “we will publish the full results of our screen as part
of another study”).
Abstract: The verb tense chosen for the abstract should be based on the section of the text to which
each sentence corresponds. For example, introductory statements describing the current understanding of
the issue should use the present tense, references to previous research should use the present perfect, and
descriptions of the methods and results should use the past tense. Indeed, one study of verb tense in
English medical abstracts has revealed that the three most commonly used tenses are past, present, and present
perfect,
in line with the conventions described here.
In this paper, we have offered some advice for choosing verb tense in a scientific manuscript. Please note
that these suggestions are not absolute rules, but following these guidelines will help your text conform to the
conventions of scientific writing. Above all, it is important to be consistent with your choice of tense. If you have any
questions about your writing, please contact us at AskAnExpert@journalexperts.com. Best of luck!
Carraway LN “Improve scientific writing and avoid perishing.” Am Midl Nat 155(2):383-394 (2006)
Lin P-Y and Y-R Kuo “A guide to write a scientific paper for new writers.” Microsurgery 32(1):80-85 (2012)
Fahy K “Writing for publication: argument and evidence.” Women Birth 21(3):113-117 (2008)
Eukaryotic Cell Instructions to Authors http://ec.asm.org/site/misc/journal-ita_abb.xhtml#01
“Writing a scientific paper” in The ACS Style Guide: A Manual for Authors and Editors ed. JS Dodd (Washington, DC: American Chemical Society, 1997)
Salager-Meyer F “A text-type and move analysis study of verb tense and modality distribution in medical English abstracts.” Engl Spec Purp 11(2):93-113 (1992)
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