Forming good sentences. How to get grammar things like tense, concord and participles right


Put away informal language and beware of mother-tongue interference


Forming good sentences in English is partly a matter of getting habituated to the native English speaker’s way of expressing him- or herself academically and putting aside the informal vocabulary and syntax to which we easily become accustomed through the media of the English-speaking world, and resisting the temptation to transfer typical features of one’s mother tongue onto English language structures at the level of words and sentences.

Most writers need a larger stock of verbs


Noun phrases or noun groups play a dominant role in most scientific fields and are fairly familiar to most researchers within a particular discipline. Moreover, most researchers intuitively know how to decompose the noun group owing to their special subject knowledge; for example in imaging diagnostics, most specialists would have no problems decoding the noun phrase brain perfusion single proton emission computed tomography imaging as a special kind of functional nuclear imaging technique (imaging = core noun).

However, most researchers need a larger stock of verbs, mainly more expressive ones. The particular features of noun phrase are discussed in another text, Writing proper English, and will therefore not be discussed her, where focus is on issues related to the verb phrase, i.e. the main verb (e.g. reported) and any auxiliaries (e.g. has been).

Use strong verbs rather than weak verbs

Strong and weak verbs

For first paper drafts, you may well use “weak”, informal or common verbs (i.e. forms of “to be, to have, to get, and find out”); but when you are refining your draft, turning it into more professional, academic writing, you may find it useful to use “strong”, formal verbs. I do not refer to the traditional distinction between weak/strong verbs according to their inflection, but use the word “strong” to indicate verbs that provide more meaning and are more concise. A few examples may illustrate the point:

Informal, weak Formal, strong
Look at

Regard, perceive, approach, study, observe, (re)view

To find out

Learn, survey, inspect, inquire, ascertain, explore, investigate, determine, uncover, analyse, calculate

To cause something to decrease

Reduce, curtail, degrade, depress, diminish, impair, lessen, restrict, weaken

To cause something to increase

Raise, advance, amplify, arouse, elevate, enhance, enlarge, enrich, heighten, improve, magnify

Some verbs take objects, others do not

The grammar of verbs

In English like in Danish and many other languages, some verbs appear only with the subject (intransitive; i.e. they do not appear with an object); e.g. I waited in the doctor’s office for a whole hour (the verb wait is intransitive, i.e. cannot be followed by an object). Other verbs appear with the subject and may take objects (transitive), both direct and indirect ones; e.g. He raised the issue at the conference (the verb raise takes object, here the issue). Many intransitive verbs describe physical movement or behaviour (e.g. His whole body (subject) was aching (intransitive verb) and his medical condition (subject) was deteriorating (intransitive verb).

Some verbs can be both transitive and intransitive. For instance, the verb administer used intransitively means to perform the activities of an administrator, whereas transitive usage encompasses “giving” like in the sentence A dose of medicine was administered. Other verbs are strictly one or the other, i.e. either transitive (e.g. lay, raise) or intransitive (e.g. die, lie, rise). In grammar generally, the verb present is only transitive (e.g. The secretary presented the dentist’s bill to me); however, in medical expert language it is often also used intransitively (e.g. The head of the foetus is presenting and The patient presented with symptoms of dyspnoea). Knowing whether a verb is transitive or intransitive may not be easy. Fortunately, most dictionaries (e.g. Oxford’s Advanced Learners’ Dictionary) give you such information through the examples they use.

Beware of groups of verbs with special meaning

Problematic verb groups

Some verbs form what we could call problematic groups. One group is imply, implication and implicate. The first two are often used in science. But beware of implicate, which always involves an element of blame or guilt. Another group where confusion often arises counts consists, contains, includes and comprises. The verb consist should be used mainly for ingredients, contain for contents; include implies less than 100%, whereas comprise means 100%. As for figure and number it is safe to reserve number for verb usage and to use figure as a noun (e.g. Females numbered 22; the figure for males was 23).

Tense use derives in part from scientific ethics

Verb tense

The use of tense in scientific articles is by no way arbitrary. Proper tense use derives in part from scientific ethics because tense use is a way of indicating the status of the scientific work that is being reported.

General use of present tense

Present tense

Present tense is used for stating what is generally true and therefore established knowledge. Thus, generalisations, references to stable conditions and general scientific “truths” should be given in the present tense. For an overview of the use of simple present, please see the table below:

Present tense
Established knowledge Denmark has one of the highest cancer incidence rates in the world
Own generalising Under these particular conditions, very few patients survive
Others’ general findings generalised

Petersen found no evidence that x exists

Your or any other’s theorising We hypothesise that obesity is caused mainly by overeating and physical inactivity
Contents of graphics
Figure 1 shows Danish lung cancer patients’ mortality rates
Explaining graphics As can be seen from Graph I, the level rises, levels off and then declines again
General use of past tense

Past tense

Simple past tense is used mainly to describe specific actions or events that occurred in the past and that are not linked to the present in the same sentence. For an overview of the use of simple present, please see the table below:

Past tense
Specific details in your or others’ published work

We found that the incidence of breast cancer was higher in 2015 than in 2014

Others’ general findings if logic demands use of past In the experiment performed by X, the test animals died during hypothermia at x degrees
Your own work being reported A total of 11 males and 9 females were included in the study
What others have said Petersen predicted that mortality would rise if X happened.
General use of present perfect

Present perfect

The present perfect (a form of the verb have plus a past participle, such as have shown or has been shown) is used to refer to a past event that is linked to the present, and trends or events that have ended or occurred recently or are still continuing, as in The past years have seen developments that are crucial to our understanding of X.  

General use of past perfect

Past perfect

The past perfect is used to describe two related past events that occurred at different times in the past, as in By the time the patients were finally admitted, they had already developed severe disease and Those patients who had been exposed to iatrogenic harm were excluded.

Tense usage varies in Introductions

Verb tense in Introductions

The introduction often includes several verb tenses that provide different contexts for the statements for which the tenses are used. First, when stating a fact that is widely accepted, the present tense is appropriate. It signifies that the statement reflects today’s understanding of the matter at hand (e.g. Genomics provides crucial information for rational drug design). This tense is therefore often used in the Introduction’s first move in steps reviewing previous literature.

Present or present perfect tense in Introductions

Most introductions also include references to previous research that is still relevant, in which case the present perfect tense is used. This tense demonstrates that the action occurred in the past but still applies in the present. A phrase like Petersen et al. have shown that Hodgkin’s disease is related to X” is appropriate to use in the context where the research or observation was made in the past, but the results remain valid today. This tense is also used when the event began in the past but continues in the present (Patients with Hodgkin’s disease have been intensively studied for the past ten years). However, the present tense is used when a specific result, figure or paper is the subject of a sentence, for example The results of their study indicate that this modality is highly effective (reference) or A landmark paper from the Department of Forensic Medicine describes a new era in the use of autopsy in Denmark.

Past tense in Introductions

In other parts of the introduction, the past tense is needed. This is the case, for example when specific reference is made to the methods used in a previous paper. For example, it is correct to write, Petersen and Poulsen analysed 96 samples and found X or Gene X was first cloned into a shuttle vector in 2003. Similarly, statements referring to facts that are no longer considered true should remain in the past tense: for instance, Early physicists thought that electrons travelled in defined orbits.

Combination of tenses in Introductions

Sometimes, a combination of tenses is necessary: Jens Overgaard suggested (past) that certain problems could (past) be related to the clinical use of thermal isoeffect doses, and subsequent work has clarified (present perfect) that such problems do exist (present).

Your use of tense shows how you relate to the research

You can indicate your opinion of the research in the Introduction by carefully selecting which tense you use. When you use the present tense, you suggest that you believe that the research is still true and relevant, even if it was conducted some time ago. If you use present perfect tense, you communicate recency or currency, either positive (asserting that previous studies have established a firm research foundation) or negative (asserting that not enough relevant or valid work has yet been done). Positive and negative currency can even be asserted in the same sentence, as in the following example of how a niche is established (Introduction: Move: Create niche; step: claim gap). Example: Much research has been conducted (present perfect, positive currency) within this field, but rather less attention has been devoted (present perfect, negative currency) to the study of X which remains (present) a controversial issue.
Past tense in Materials and Methods

Verb tense in Materials and Methods

The past tense dominates Materials and Methods sections since they report what was done during the course of the study. You may use either the active voice, e.g. We tested (past, active) independently derived cultures for resistance to X or the passive voice, e.g. Cells were transfected, irradiated and assayed (past, passive) for any damage to their DNA. Evidently, as discussed above, where two events in the past are linked, the past perfect tense is 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 had + –ed or –en) of a verb; e.g. Patients who had decided (past perfect) to undergo surgery completed (past) the pre-surgery check-up.

Past passive or past active in Materials and Methods

Tthe choice of active or passive voice whether through use of past passive or nominalization is one of focus. In the past passive (e.g. The patients were randomised (past, passive) by drawing lots between them or in the sentence 50 cl ascites was drawn from the pleural cavity, the focus is on the object (i.e. the patients in the first sentence and 50 cl ascites in the second); in the past active voice (e.g.  We randomised (past, active) the patients by drawing lots between them or in the sentence Each of the nurses drew (past, active) 50 cl ascites from the pleural cavity) the focus is on the doer (viz. we and each of the nurses); and in nominalisation (e.g. Randomisation (noun formed from the verb to randomise) was performed by drawing lots between the patients), the focus is on the process or action performed (i.e. the act of randomizing).

Present tense in Materials and Methods

When using graphics to help explain what was done, the present tense is used to refer to the figures or tables; e.g. Table 1 shows the process of cloning used in the present study.

Past tense in Results

Verb tense in Results
Like the Materials and Methods section, the Results section of a manuscript is also written mainly using the past tense, e.g. We detected no virus in the control sample or All participants reported a significant improvement in quality of life.

Tense shows how you relate to your data

Please note that usie of the present tense is usually not recommended when reporting your results in order not to inflate their robustness and generalisability. You should rather use the past tense. Please consider the following examples: We have determined that the association between X and Y is Z where the results are presented as generally accepted truth). In this text sample, however: In this study, the association between X and Y was Z , the association applies only within the boundaries of the study being reported.

Present tense in Results
As described for the Introduction, the present tense is used when reference is made to the entire paper or to individual manuscript elements like figures, tables or data, e.g. Figure 1 shows a significant effect of X on Y. Moreover, the present tense is used when graphics are explained; e.g. As may be seen from Graph 1, the level rises and reaches a plateau at…
Mix of past and present in Discussions
Verb tense in Discussion The rules that apply to the use of tenses in the previous sections also apply to the Discussion section. The past tense is used to summarise findings in combination with the present tense to explain or interpret what the results mean; e.g. As maximum effect was reached (past) within the first hour, it is possible that the effect may be (present) only transient. The present tense is also used when conclusions are presented (e.g. We conclude (present) that X is (present) a valuable supplement in the treatment of Y).

Use “will” to express future in the Discussion

However, the discussion also includes the simple future tense where directions for additional research or scholarship are brought up, but note that in medical science it is customarily only the auxiliary verb will that is used to express future; e.g. The approach reported here will (future) allow for efficient monitoring of disease progression or We will (future) publish the full results of this part of our study in a later paper.

Mix past and present tense in Conclusions

Verb tense in Conclusion

In the final section of the paper, the main findings and the major implications of the study are usually summarised, limitations may be mentioned and suggestions for future research may be offered. This requires the use of a combination of tenses. The following example illustrates tense use in a Conclusion: Although the study found (past) evidence of X, the data did not allow (past) us to determine its effects on Y. Further studies are (present) therefore needed to clarify this issue.

Twenty rules of subject-verb agreement

Subject-verb agreement

In English, subject and verb agree in number, which means that singular subjects need singular verbs, and plural subjects need plural verbs. There are roughly 20 rules of subject-verb agreement, which may easily be learned. For example, X gene (singular subject) has (singular verb) recently been implicated in this disease or Several genes (plural subject) have (plural verb) recently been implicated in this disease. You may find many useful resources on the Internet for non-native English speakers, including small tests. The present paper will therefore deal exclusively with the cases that traditionally pose problems to writers of medical science papers who are not native English speakers.

The real subject decides the number of the verb

Mistaken subject

Words that come between the subject and the verb may distract the author from the real subject of the sentence. For example, in the sentence Basic experiments using an animal model was not to be conducted the real subject is Basic experiments, which is followed by an intervening phrase (using an animal model) , so the verb was (singular) is incorrect. In this sample sentence, the noun (model) is distracting because it is closer to the verb than the real subject. The correct verb is were.

With either..or / neither…nor the closest noun decides

Multiple subjects joined by either..or / neither..nor In these cases, the rule of ‘proximal noun’ applies, i.e. the verb agrees with the subject that stands closest to it, e.g. Neither the patient’s family doctor (singular noun) nor his family members (plural noun) were (plural verb; agrees with closest noun) informed about his admission to hospital. The rule also applies if we reverse the order of the sentence elements: Neither the patient’s family members (plural noun) nor his family doctor (singular noun) was (singular verb; agrees with closest noun) informed about his admission to hospital.
Positive always wins over negative

This rule of proximity is, however, overridden by another rule, which says that where two elements in the subject phrase are conjoined, the ‘positive’ element always wins. So if one of the two conjoined nouns is negated and the other is not, concord is always with the non-negated element. In the following example The patient’s family doctor but not his family members was informed about his admission to hospital members, we have a conjoined subject that consists of a singular, non-negated noun phrase (The patient’s family doctor) AND a plural, negated noun phrase(but not his family members), so therefore the verb should be singular, i.e. was. Similarly, The patient’s family members (plural, non-negated noun phrase), but not his family doctor (singular noun, negated noun phrase) were (plural verb; agrees with non-negated noun phrase) informed about his admission to hospital.

False singular and plural nouns

False singular/plural nouns

Certain words of Latin or Greek origin may pose problems because the plural form of these words is not formed by just adding –s to the root of the word. Examples include analysis/analyses; bacterium/bacteria; criterion/criteria; pharynx/pharynges; phenomenon/phenomena.

Some words are false plurals and only take singular verbs (e.g. ascites, herpes, genetics, measles, mumps), while others take only plural (e.g. adnexa, genitalia); and some have only one form (series, facies, forceps, biceps, triceps) and you must decide from the context whether it is plural or singular.

Singular for measured items
Measured items For measured items, the verb is singular; e.g. An amount of 10 ml was (singular) administered; Six weeks is not enough to ascertain any effect of the intervention.

Singular with singular or non-count noun

Fractions, percentages and indefinite quantifiers (e.g., all, few, many, much, some)

The rule of proximity mentioned above also applies in case of fractions and percentages. For example, a singular verb is used with a singular or non-count noun:

  • One-third (fraction) of this article (singular noun) is (singular verb) discussion of our results
  • Much (quantifier) of the book (singular noun) seems (singular verb) relevant to the issue at hand
  • Fifty per cent (percentage) of the job (singular noun) is (singular verb) routine.

Plural with plural noun

A plural verb is used with a plural noun; e.g.

  • One-third (fraction) of the patients (plural noun) have (plural verb) suffered iatrogenic harm while admitted to hospital
  • Many (quantifier) researchers (noun, plural) believe (plural verb) that writing is easy
  • Fifty per cent (percentage) of the interviewees (plural noun) usually respond (plural verb) to all items.

With “majority/minority”, verb number depends on situation 


When majority/minority refer to an unspecified number, meaning more or less than 50%, the singular verb is used; e.g. The majority has no strong view on this issue; A small minority says that it backs the proposal. However, when majority/minority is accompanied by a specific percentage, it is possible to use either a singular or a plural verb: A 75% majority have/has argued against changing the organisation; A 10% minority are/is opposed to the proposed change.

When majority/minority refers to a specified set of persons, a plural verb should be used: A majority of patients have decided to accept the invitation; A minority of the doctors have expressed reluctance to engage in continuous medical education.

“Number of” singular with single quantity, plural when used as indefinite quantifier

Number of

In phrases where the phrase number of is used, the number of the verb depends on the meaning of the phrase. Such phrases take a singular verb when they refer to a single quantity; e.g. The number of patients registered in the protocol is (singular verb) 120 (single quantity); but they take plural verbs when they are used as indefinite quantifiers: A number of (indefinite quantifier) patients were (plural verb) missing.

Participles are verbs functioning as adjectives


A participle is a form of a verb that does not act as a verb but as an adjective, for example. In the sentence The filtered water tastes good, the word filtered is a participle derived from the verb to filter, and it acts as an adjective, characterising water.

A participial phrase functions as an adjective

English has two types of participles: the present participle, which may be recognised from the ending (-ing), and past participle of regular verbs that end in –d or –ed and irregular verbs that may end in –t or –en.

Participles are used in various ways; but here the focus is on how they are used and misused in phrases and clauses (subordinate sentences). Participles can appear in a participial phrase that consists of a participle and a complement or modifier, so that all the words in the participial phrase come together, acting together as an adjective. For example, in the sentence Flying above the field, the eagle looked majestically the participial phrase Flying above the field consists of a participle (Flying) and a prepositional phrase (above the field) which describes the noun (eagle) in the sentence the eagle looked majestically.

Look out for participial phrases in the beginning of sentences

It is sometimes difficult to determine which noun a participial phrase is modifying because the noun that it is intended to modify is not stated explicitly in the sentence. When this happens, the participle is called “dangling” because it has nothing to modify. Participles standing first in sentences may be problematic because they do not have explicit subjects. Let us consider a few sample sentences

  • Structured into various sections, the readers of this text can choose the topic of primary interest
  • Paying attention to the rules of grammar, most texts can be improved
  • Based on experience, microsomal preparations are more useful than hepatocytes

In these sample sentences, the participles describe the wrong words. In the first example, the participle does not describe the object (texts) but the subject (readers). The sample sentence should be rewritten to make sense: The text is structured into various sections, which allows the reader to choose the topic of primary interest. In the second sample sentence, texts cannot pay attention, so the sentence should be rewritten to: Most texts can be improved if writers pay attention to the rules of grammar. In the third text sample, it is hardly microsomal preparations but the conclusions that are based on experience. The sentence could be rephrased to: Experience shows that microsomal preparations are more useful than hepatocytes or: We consider microsomal preparations more useful than hepatocytes.

When you proofread your texts, make a habit of asking yourself if it is clear which element in the sentence is modified by the participle, and if this is not perfectly clear, consider rewriting the sentence to make it unambiguous.

Using often dangles

Using is one of the participles that most often dangle, whether in fronted adverbial phrases or adverbial phrases placed in other sentence positions. Consider these examples: Using lasers, the patients’ eyes were examined; The disease was studied using the latest technology; The children were examined using X. In these examples, it would be appropriate to change using to with (indicating instrument; e.g. The patients’ eyes were examined with a laser) or by (The children were examined by use of PCR analysis). It is, of course, okay to use using with an agent, e.g. Using X, we examined the children.

Put elements that belong together near one another
Participles ending in –ing may easily become dangling. Consider for example the following sentences: After preparing the samples, our focus was on collecting the data; Hanging from the ceiling, the doctor noticed an electrical cable. The participles obviously describe the wrong nouns here. The sentences should be rewritten so that elements that belong together stand together, e.g. into After preparing the samples, we focused on collecting the data and The doctor noticed an electrical cable hanging from the ceiling.
You can avoid dangling participles

In order to avoid dangling participles, make sure that the implied subject of the action that lies in the participle is actually the subject doing the action, and write in active voice whenever possible.

Assuming, considering and according to are okay

Some dangling participles have become so common in scientific language that they are today accepted by many journals and are therefore no longer considered poor language use. Such examples include the use of assuming, considering, and according to; for example, Assuming the trial is successful, the experiment will proceed; Considering the importance of our data, the study will continue; According to the methods section, the number of subjects recruited was small.

Infinitives can also dangle

Dangling infinitives

The infinitive (e.g. to determine) may also be hanging, i.e. if it introduces a subject (doer) who is not present in the text; e.g. To determine whether X changed during the course of the experiment, blood was sampled at regular intervals. In this sentence ,the subject of the main sentence is blood, but the implied subject of the phrase To determine.. etc. is the investigator! Some journals  do accept dangling infinitives, notably in the Materials and Methods sections., but most journals do not accept them.

Dangling gerunds

Words ending on –ing may function not only as adjectives (participles) but also as nouns gerunds. And just like participles, gerunds may be dangling, i.e. they may be standing in the wrong places in sentences and the implied subject of the phrase may not be the subject of the main sentence. Consider, for example, the following sentence: By talking with the patients, the situation was made clear. Here the sentence will make more sense if the implied subject is inserted!  By talking with the subjects, we clarified the situation.

Struggling with dangling participles, infinitives and gerunds is not a prerogative of the non-native English speaker. It may be comforting to know that many native speakers also struggle with this. You may want to consult this site for a nice overview of dangling phrases.