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English Corner

Scientific English grammar and style   English Corner   Glossary of English grammar and style  

English Corner 11: tenses of verbs

The three tenses used in scientific writing (the future, for action going to happen or to be the case in time to come; the present, for action happening or being the case now; the past, for action having happened or being the case in the past) each have two forms. The simple forms refer to individual events done once, being done once now or to be done once in the future and the perfect (or completed) forms which refer to results which were initially done only once but are reproducible and have consequences that are still valid at the time of writing.

The simple future tense
This refers to some future time and employs the auxiliary verb shall/will with the infinitive without the infinitive marker to [I shall/he will culture the cells on Monday next week]. The written form may differ from that of the spoken word where the future tense of the verb to be and a continuous (or imperfect, because uncompleted) verb form (present participle) may be used [If you come at 11.00 I shall/he will be culturing the cells].
In manuscripts it is used to state what you plan to do, whether active [We shall next examine the regulation of these transporters] or passive, with the future tense of the verb to be and a past participle [The regulation of these transporters by osmolality will be examined next].

The future perfect tense
This is used for considering actions that will be completed (or perfected) at some future time. It is formed from shall/will and the present perfect (see below) whether active [If you come at 13.00 I shall/he will have finished culturing the cells. By the time the grant application has been submitted I shall/he will have completed the manuscript] or passive [If you come at 13.00 the cultures of the cells will have been finished. The manuscript will have been completed by the time the grant application is submitted].
An anomaly of the future perfect tense is that when two such verbs are present in a sentence, the one in the subordinate clause is elided [omitted from the text but provided mentally by the reader] so that the nominally correct form [When I [shall] have finished my work, I shall come to see you] is presented verbally and orally with ellipsis [When I have finished my work, I shall come to see you].
If the future perfect is used with an infinitive, there is a temptation to write both verb forms in the future perfect tense [I should have liked to have been there. I had planned to have finished it yesterday] when only one needs to be. These sentences should either have only the present perfect of the infinitive [I should like to have been there. I planned to have finished it yesterday] or of the auxiliary verb [I should have liked to be there. I had planned to finish it yesterday].

The simple present tense
This refers to the present time. What is written as a statement of fact [Every Tuesday I culture the cells] may differ from the spoken word employing a continuous verb form (imperfect), with the present tense of the verb to be and a present participle [Don’t come now as I am culturing the cells].
In manuscripts the simple present tense is used for accepting as correct others’ conclusions [Hyperactivation precedes the acrosome reaction (Jones et al. 1978)]. It may seem incongruous that the present tense is used for past work, but it is used only with reproducible work generally accepted to be sound knowledge. Although the work may have been done once (published in 1978), every time it is repeated the same results are obtained. Similarly, the simple present is used for conclusions from the current reproducible results [Our work shows that temperature affects sperm motility].
This usage resembles that of universal statements, which appear to be factual conditional statements [If you heat water, it boils] but are not true conditionals because if can be replaced by when or whenever [When you heat water, it boils. Whenever you heat water, it boils], meaning that every time that the action is performed, the same result is obtained.
By the same reasoning (every time the paper is read the data are to be found in Table 1 and Figure 2) the simple present is used to indicate where the results are to be found [The data are presented in Table 1 and Figure 2].

The present perfect (or perfect) tense
This is used for reports that are completed (or perfected) at the present time, and whose reproducible results may still be valid today. It is formed with the present tense of an auxiliary verb and a past participle with the main statement also in the present tense, to denote accepted knowledge, whether active [Jones et al. (1974) have shown that hyperactivation precedes the acrosome reaction] or passive [It has been shown that hyperactivation precedes the acrosome reaction (Jones et al. 1974)].
It is also used for what is concluded from the reproducible results of work being written up [This work has shown that temperature affects volume regulation].

The simple past (or definite past) tense
This refers to the past time. What is written as a statement of fact [Last Wednesday I cultured the cells] often differs from the continuous tense spoken form with the simple past tense of the verb to be and a present participle [Last week at this time I was culturing the cells].
In manuscripts the simple past is used to describe what was done [The spermatozoa were incubated for 4 h at 37°C] and to state what was found [After drug treatment there was a drastic decrease in motility].
The simple past is also used describe published work where the emphasis is on the one occasion that the work was done. The verb in the that clause is also in the simple past tense, to emphasise that only the individual results on that occasion are being discussed [In 1978 (not 1980) Jones et al. (not Hinton et al.) showed that hyperactivation preceded the acrosome reaction].

The past perfect (or pluperfect) tense
This is used for reports that were completed at some past time, and whose reproducible results may still be valid today. It is formed with an auxiliary verb in the simple past tense and the main statement also in the present tense, to denote accepted knowledge [By the 1970s it had been shown that hyperactivation precedes the acrosome reaction].

Reported tense
When text is reported there may be a change from the original tense depending on the nature of the reporter and how it is quoted.
When the present tense is reported in the third person singular, for direct quotations (where the words actually spoken or written are cited within quotation marks after X said “…”) the original tense is retained. If the words Cooper spoke were “The regulation of volume is (present tense) an important sperm function”, the direct quotation retains the present tense [Cooper said, “The regulation of volume is (present tense) an important sperm function”]. For indirect quotations (where the spoken or written words are paraphrased without quotation marks after X said that …) the tense changes to the simple past [Cooper said [simple past tense] that the regulation of volume was [simple past tense] an important sperm function].
Similarly for statements of first and second persons in the future tense with auxiliary verbs [I shall be retiring in 2009. You will live to regret it], the first and second person simple past tense of the auxiliary verb is used in indirect reports in the third person [He said that he would be retiring in 2009. She said that I should live to regret it].
When there is self-reporting of statements made in the first person singular or plural [I shall arrive tomorrow. We shall have finished by the weekend], the reports take the simple past tense of the first person of the auxiliary verb, be they future-in-the-past [I thought that I should arrive on Monday] or future-perfect-in-the-past [We believed that we should have finished by the weekend].
When reported in the second or third person singular the simple past tense of the second or third person of the past auxiliary verb is used [You said that you would arrive on Monday. They said that they would have finished by the weekend].
If what is said is stylistically incorrect, the words quoted depend on whether the quotation is direct or indirect. If the words spoken were “It is possible (indicative) that it could be (conditional) due to a vitamin-deficiency”, where both possible and could indicate uncertainty when only one such word is necessary, for direct quotations the spoken or written words are retained [He said, “It is possible that it could be [sic] due to vitamin-deficiency”, where [sic] indicates that the words have been given verbatim and include uncorrected  errors) but for indirect quotations, judgement may be used when paraphrasing to correct the style [He said that it was possible (indicative) that it was (corrected to indicative) due to vitamin-deficiency].

Examples of how tenses may vary in each part of a manuscript follow
Title
Abdominal temperatures reduce [simple present: conclusion from present reproducible results] sperm motility.
Introduction
It has been shown [present perfect: previous reproducible work valid today] that temperature influences [simple present: accepted knowledge] male fertility. As scrotal temperature is [simple present:
accepted knowledge] 34°C the effects of temperature on sperm function were examined [simple past: what was done] in this report.
Methods
A medium containing 15 mM inositol was prepared [simple past: what was done] in BWW and the sperm suspension was incubated [simple past: what was done] for 10 min at temperatures ranging from 30 to 37 °C. Sperm motility was measured [simple past: what was done] by CASA at each temperature.
Results
High incubation temperature reduced [simple past: the results] the motility of spermatozoa. Fig 1 shows [simple present: where the results are] that above 35°C there was [simple past: the results] a sharp decline in forward progression. The mean kinematic parameter values at each temperature are [simple present: where the results are] presented in Table 1. The data show [simple present: conclusion] that there was [simple past: the results] a biphasic relationship between temperature and sperm motility characteristics.
Discussion
The current work has shown [present perfect: present reproducible work] that the motility of spermatozoa is [simple present: conclusion from present reproducible results] temperature-sensitive under the conditions employed. This accords with the tenet that scrotal temperature influences [simple present: accepted knowledge] the functional responses of spermatozoa. The effect of temperature regulation on volume regulation by spermatozoa will be examined [simple future: what will be done] next.
Conclusion
This work has shown [present perfect: present reproducible work] that sperm motility is affected [simple present: conclusion from present reproducible results] by temperature.
Acknowledgments
This word was funded [simple past: what was done] by Contraceptives Anonymous (Grant No. 123abc).

By Dr Trevor G Cooper (ctrevorg@gmail.com)

 
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