The verbal group: tenses

The Research Paper
The Research Paper makes much more use of past time. In the second paragraph of the
Introduction the writer is describing the experimental work of Lufton and Sowerby and
what they found:
Lufton and Sowerby (1)
provided
some evidence for the atherogenic role of lipid peroxides.
They
showed
that the content of peroxides in lipids extracted from the human aortic wall

increased
the degree of atherosclerosis. They
extracted
the lipid however, by mixing the
tissue exposed to the air, with anhydrous sodium sulphate and extracting the mixture with
chloroform at room temperature. These treatments may have caused the artifactual
formation, by oxidation, of peroxides from unsaturated lipids during the extraction. We have
therefore reopened the question of whether lipid peroxides occur in aorta lipids, using aerobic
extraction at much lower temperatures in order to minimise oxidation.
In the first part of this paragraph the writer is discussing experimental research that
was completed and the findings that have been accepted by the scientific community as
facts. The simple past tense is used.
However, notice how the writer shifts to the present perfect tense (underlined) when
he/she wants to challenge part of the findings that are of direct relevance to the

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Basic English Grammar Module: Unit 2B. Independent Learning Resources
© Learning Centre University of Sydney. This Unit may be copied for individual student use.
22
research work that is currently being carried out. The researcher challenges the
methodology by using the modal "may" and by the use of the present perfect tense,
which indicates that although this took place in the past, it is still of relevance to the
present research.
In the Materials and Methods section there is consistent use of the simple past passive as
this is a description of procedures that were completed in the past.
Aortas were obtained at autopsy, within 6-­‐12 hours of death, at the University Hospital,
Barchester.
The Discussion section also makes use of the present perfect when reference is made to
previous research that is related to the current research
"It has recently been discovered (6) that arterial lipids become progressively more
unsaturated with increasing degree of atherosclerosis.
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Exercise 9

The following is an Introduction from a research paper. The main verbs have been

underlined. Answer the questions below the text.
Aquatic hyphomycetes in freshwater habitats can be distinguished into the Ingoldian and the
aeroquatic groups (Webster & Descals, 1980). The Ingoldian hyphomycetes