Forming Sentences Grammar

The Farlex Grammar Book

Complete English Grammar Rules

Get Instant Access

"There's a great power in words, if you don't hitch too many of them together."

Josh Billings


We may know much about the proper structuring of a paper and correct spelling of words, but this does not suffice to produce a compelling manuscript. Ultimately, the power of our text hinges on the competent use of the English language. If your native tongue does not happen to be English, using proper and powerful grammar may be more difficult, but even if you are a native English speaker, you may occasionally struggle with English grammar and its proper use in scientific writing.

Sometimes, students of scientific writing point out that it is hardly worth their while to pay close attention to grammatical detail, knowing that few readers will appreciate their special effort and that most will have a language origin other than English. While there is some truth in this, I would argue that it is precisely for this very reason, i.e., just because many readers are non-native English speakers, that we owe it to the scientific community to write in a clear and unambiguous style. Remember that the main purpose of communicating within the sciences is to pass on pertinent information that is read and understood by the intended audience.

As I have pointed out in earlier sections, this book is not about English grammar as such. There are many excellent books on English grammar and usage that you may wish to consult if you have specific questions. When talking about grammar in workshops and lectures, students often point out some basic rules of English grammar they remember from their school days. What about splitting infinitives? Can we end a sentence with a preposition? Do singular subjects always take singular verbs? The good news is that most of these basic rules of grammar are outdated and have little value in scientific English. The most important rule of grammar in scientific communication is to convey meaning to the reader. A clear sentence is a good sentence, even if so-called rules have been broken. Alternatively, you may produce a sentence with impeccable grammar that means absolutely nothing to the reader.

Here, our focus is clearly on the use of the English language to convey scientific messages to the learned audience. Because good scientific writing requires proper use of the English language, we will, however, have to look at some aspects of grammar. This section addresses some typical questions of grammar and usage in connection with scientific writing. The section is by no means exhaustive; it merely focuses on the topics I consider most troublesome, and whose proper handling will add the greatest power to your scientific messages.

Table 4.1 defines the main grammatical elements we use in scientific reporting. Consulting this table may help when a specific word type or other structure needs to be identified.

Table 4.1 Grammar in Brief




Grammatical construction containing a subject and an action


Responsible for the action in a sentence


Word naming a concrete (e.g., book) or abstract (e.g., love) thing


Word replacing a noun (e.g., he, she, that)


Adjective (modifying a noun), adverb (modifying an adjective or a verb), or noun (modifying another noun)


Group of words acting as a noun or modifier


Group of words acting as a noun or modifier, containing a subject and a verb (in contrast to a phrase)

Metaphor / simile

Word or image used to describe something not like itself (e.g., the "head" of a company)


I usually start my lecture on the tenses in scientific reporting by reassuring my students and workshop participants that "there is no need to get tense about the tense." We just need to know a few rules governing the correct handling of the tenses.

Proper use of tense in scientific documents derives from scientific ethics, i.e., we owe it to the scientific community to declare, by the choice of tense, whether we report established facts or new, previously unpublished data. When a scientific paper has been published in a primary journal (i.e., a journal that publishes only original data), the information communicated becomes "established knowledge." This definition often creates heated discussion among my students as they point out, quite rightly, that so many a published "fact" will be proven untrue in subsequent publications. In this respect, "established knowledge" occasionally turns out to be a transient phenomenon. Nonetheless, validly published findings are regarded as "knowledge" as long as the findings have not been challenged or even disproved elsewhere.

Let me reassure you that you will hardly ever encounter the situation where the distinction between established knowledge and new results presents a problem. When you describe the scientific context of your work, for example the disease your work deals with, you will automatically use the present tense to detail what is known about the incidence, prevalence, cause, and perhaps therapy of the disease in question.

^ Established knowledge: HIV infection is highly prevalent in African countries [12].

Your own new finding: Inhibition of the enzyme resulted in much higher plasma levels of the parent drug.

When referring to your finding after its publication: Inhibition of the enzyme results in much higher plasma levels of the parent drug [2].

Therefore, the two tenses mainly used in scientific writing are the simple present and the simple past. The so-called perfect tenses (e.g., have been, had been) should be used sparingly. The perfect tenses are appropriate only if we refer to a moment in time before the reporting time point (requiring the past perfect), or if we describe a state of progression or a situation that is still persisting (requiring the present perfect).

^ Immediately after puncturing, a stopwatch was started and the blood absorbed every 10-15 sec using the edge of a piece of filter paper until all visible bleeding had ceased. (past perfect)

Only those mice that had previously been injected with the study drug were included in the experiment. (past perfect) The Department of Physiology has been located in Building 221 since 1985. (present perfect)

Thus, the rule to remember is this:

Q Report established knowledge in the present tense, but new, previously unpublished findings (including your own results) in the past tense.

Difficulties often arise when referring to attributions or data presentations (see Table 4.2). It is correct to say, "Miller [10] showed that the cure rate in infected outpatients is approx. 15%." In your manuscript or report, it is also correct to say, "Figure 1 indicates that younger subjects had a higher chance of responding to treatment."

Table 4.2 shows the tense appropriate in a specific context or section of a scientific manuscript.


Table 4.2 Rules for Applying the Appropriate Tense



Established knowledge, previous results etc.

Present tense

Methods, materials used, and results

Past tense

Description of tables and figures

Present tense, e.g., Table 5 shows ...; Figure2 illustrates ...


Past tense, e.g., Jones et al. reported that...; Daviesfound ...

In a typical scientific paper, correct use of these rules will inevitably result in tense changes, sometimes within the same section. Many writers wrongly assume that the same tense, e.g., the present tense or past tense, should be applied to the entire manuscript or report. With the distinction between established and new findings in mind, this is clearly not possible, nor would it be correct.

Choosing the correct tense is hardest in the Discussion section. Here, we may emphasize the relationship of our work to previously established knowledge, using attribution to other workers and referring to reported findings. Moreover, we may express a personal opinion, which should be in the present tense (e.g., "We feel that these findings indicate ... ", "It is our opinion ... ", "We emphasize that ... "). Occasionally, there may be a need to announce further actions (e.g., "Further studies to examine the mechanism will be done."). As a general rule, future work should be mentioned with caution because so many planned experiments and studies never actually get off the ground.

Table 4.3 shows the tenses predominantly used in the various sections of a paper or report. Clearly, there may be a switch from the present to the past, and vice versa, even within individual sections of a paper. If we let common sense prevail, we can avoid most errors in the choice of the appropriate tense.

Table 4.3 Tenses Typically Occurring in a Paper or Report



Abstract / Summary



Mostly present tense (established facts, previously published data)

Table 4.3 (Continued) Tenses Typically Occurring in a Paper or Report



Materials / Methods




Discussion / Conclusions

Mixture of past and present, sometimes future tense

Q Exercise 5



Confused scientific writing often comes about by erroneously joining sentences, clauses, or even single terms. The resulting incoherence is called "nonparallelism." I would argue that nonparallelism is, indeed, responsible for many errors, some of which are serious enough to lead the reader to draw the wrong conclusions. Nonparallel statements often come about because we think faster than we write, or because we expect the reader to deduce the correct message from our statements although the text is unclear. Another reason for the many nonparallel sentences in science is carelessness, an attitude grossly incompatible with the enormous precision we exercise when doing scientific work. Please bear in mind that it is unfair to the readers of our paper to let them guess what we were trying to say.

Nonparallel statements may occur on all levels of a sentence, for example, when joining nouns, verbs, modifiers, prepositional phrases, or entire sentences. The joining words are called conjunctions, and these may be of the coordinating or subordinating type (Table 4.4). Coordinating conjunctions join terms that are equals, whereas subordinating conjunctions show inequality or a relationship of dependence or limitation. Both types of conjunctions may be involved in nonparallel constructions.

Table 4.4 The Two Types of Conjunctions




and, or, but, for, nor, so, yet


if, as, when, because


Let us consider some nonparallel statements typically occurring in scientific or medical reporting:

^ Incorrect: The department was responsible for recruiting, monitoring, and analyzing the data.

This sentence implies that "data" were recruited and monitored, when, in fact, it was the patients who were recruited and the trial that was monitored. The sentence should be reworded to make this clear:

^ Correct: The department was responsible for recruiting the patients, monitoring the trial, and analyzing the data.

Another source of nonparallel statements is the change of verb number within the sentence:

^ Incorrect: A small volume of water was added to the mixture and the samples incubated for 24 h.

Here, the second verb should be "were," but this was simply skipped. The second verb can only be omitted if the verb number (i.e., singular or plural) is the same.

^ Correct: A small volume of water was added to the mixture, and the samples were incubated for 24 h.

Joining transitive and intransitive verbs can also lead us astray:

^ Incorrect: Her publication on current therapies far surpasses and is clearly superior to previously published reviews.

Here, the transitive verb "surpasses" requires an object and therefore cannot stand alone. The assumed object in this example is "published reviews," but it is incorrect to join the transitive verb (surpass) and the intransitive verb (is) via the conjunction "and." This is one way of correcting the sentence:

^ Correct: Her publication on current therapies far surpasses any previously published reviews and is clearly superior to the available literature.

We have restored grammatical parallelism, but the style of the sentence may be questioned because to surpass something and to be superior to it is a tautology [see also 6.3, Tautology]. I suggest the following:

^ Correct and preferred: Her publication on current therapies is far superior to any previously published reviews.


Lack of parallelism often occurs when comparing things:

^ Incorrect: In this study, the new compound was as efficacious but safer than the comparator drug.

Here, "efficacious" is erroneously linked with "than." The term should have read "as efficacious as the comparator drug" to restore grammatical parallelism. We may overcome this lack of parallelism by rewording the sentence:

^ Correct: In this study, the new compound was as efficacious as the comparator drug but was safer.


When joining prepositional phrases, the temptation to produce a nonparallel sentence appears to be overwhelming.

^ Incorrect: These templates are for your clinical staff, and for when they plan to design a large clinical study.

This sentence raises questions. Are the templates for all members of your clinical staff, or just for those who plan to design a large clinical study? Are the templates of general use, or are they just suitable for the design of large clinical studies? Well, we could speculate on the intended meaning of the sentence for hours and would still not know for sure.

Here is another troublesome statement suffering from a nonparallel structure:

^ Incorrect: This new laxative was developed for patients with hemorrhoids, anal fissures, and after surgery.

Do we have the correct number of "ands" in this sentence? We can easily see that the first part of this compound sentence "This new laxative was developed for patients with hemorrhoids, anal fissures" is incomplete. In parallel sentences, each clause should be able to stand independently. The sentence can be cured of its nonparallel structure by adding the missing "and" and repeating the object of the sentence (i.e., "patients").

^ Correct: This new laxative was developed for patients with hemorrhoids and anal fissures, and for patients who had undergone surgery.

Q For parallelism, the term(s) linked via a conjunction must have the same grammatical structure.

Q Exercise 6


It is important for writers to pay attention to subject-verb agreement because errors can lead to gross confusion. In principle, the story is a simple one: a singular subject takes a singular verb, and a plural subject takes a plural verb. This simple rule works in most cases and should thus be followed wherever appropriate.

^ Correct: The study shows the importance of measuring blood concentrations at the specified intervals.

Correct: The studies show the importance of measuring blood concentrations at the specified intervals.

One of the problems is that we are often unsure of the subject in the sentence, especially if the sentence is long and the verb is far removed from its subject. Sometimes, such sentences can be cured of their lack of subject-verb agreement by rearranging the syntax.

^ Incorrect: The generation of excessively large sets of data were responsible for the delay in finalizing the study.

Incorrect: The effects of alcohol on enzyme induction was studied in vitro.

The subject of the first sentence is "generation," a singular noun requiring a singular verb (i.e., was). In the second sentence, the subject is plural (i.e., "effects"); thus, the plural "were" is correct. If in doubt, temporarily ignore all phrases between the subject and verb, and the actual sentence becomes readily apparent.

^ Correct: The generation of ... data was responsible for the delay in finalizing the study.

Correct: The effects ... were studied in vitro.

Another frequent problem is the erroneous use of plural terms. Many writers use plural words as singular nouns, not realizing that these terms have, in fact, a matching singular form. Table 4.5 shows some typical examples of plurals erroneously used as singulars.

Table 4.5 Plural Nouns Requiring Plural Verbs



The main study criteria was the reduction in death rate at the end of the 3-month treatment period.

The main study criterion was the reduction in death rate at the end of the 3-month treatment period.

The data was analyzed descriptively.

The data were analyzed descriptively.

The causative bacteria was identified.

The causative bacteria were identified.

The media used in the incubation experiments was free of glucose.

The medium used in the incubation experiments was free of glucose.

Or (if several media were used): The media used in the incubation experiments were free of glucose.

Q In general, a singular subject takes a singular verb, and a plural subject takes a plural verb.


A few nouns are plural in form but singular in meaning (e.g., news). Other nouns have no plural form and therefore always take the singular verb (e.g., information). Moreover, some singular nouns look like plurals because of their "s" at the end (e.g., measles). Table 4.6 shows examples and correct use of such special nouns.

Table 4.6 Using Special Nouns Correctly




This is news to me.


Information on patient compliance was collected during the study.


Nowadays, measles is rare in Western countries.


Mumps is often accompanied by complications.

Was this article helpful?

0 0
Kindle Power

Kindle Power

The biggest benefit of publishing your own Kindle book is to position yourself as an expert. People respond to experts and they perceive anyone who has authored a book as an expert in that particular field. Your Kindle book doesnt have to be that long but it does need to provide useful and practical advice to people. You need to take this into account when preparing your book.

Get My Free Ebook

Post a comment