Active and Passive Voice

Lesson 4: The Passive with Modal Verbs

Lesson: 4 of 7 | Level: 🟠 Intermediate — 🟣 Upper-Intermediate

1. Lesson Overview

Modal verbs and the passive voice interact in ways that are both grammatically straightforward and communicatively powerful. The combination of a modal verb with a passive construction allows speakers and writers to express necessity, obligation, possibility, permission, certainty, and advice about actions — while simultaneously foregrounding the patient rather than the agent, maintaining objectivity, and avoiding the specification of who is responsible for performing or receiving the action.

Modal passives are particularly important in academic, scientific, legal, and formal writing — where expressing what must, should, can, or may be done is a constant requirement, and where the impersonal, objective tone of the passive is highly valued. This lesson examines every major modal passive construction in full — present, future, and past — with the most comprehensive treatment possible.

Objectives

By the end of this lesson, you will be able to:

• Form modal passive constructions correctly in present, future, and past forms
• Apply all major modal passives — must be, should be, can be, may be, might be, could be, will be, would be, shall be, ought to be, had better be, and need to be
• Use modal perfect passives — must have been, should have been, could have been, etc. — correctly
• Recognise and correct common errors in modal passive construction

2. Core Content

A. Forming Modal Passives

The structure of all modal passive constructions follows the same principle established in earlier lessons:

Modal verb + be + past participle (present/future passive) Modal verb + have been + past participle (past/perfect passive)

The form is the same for all persons — modal verbs never change for person or number, and the passive elements (be and past participle) are invariable in modal constructions.

B. Must Be and Must Have Been

Must be — present/future necessity or logical deduction in the passive

Must be + past participle expresses strong necessity, obligation, or logical certainty about a present or future action — in an impersonal passive construction.

For example:

All data must be archived in an accessible and durable format within thirty days of collection. The instruments must be calibrated before each dive to ensure the accuracy and reliability of the data collected. The temperature at that depth must be maintained at a constant level — any variation would be detected immediately by the monitoring system.

In the first two sentences, must be expresses obligation — what is required. In the third, it expresses logical certainty — what the speaker deduces must be the case.

Must have been — past logical deduction in the passive

Must have been + past participle expresses confident logical deduction about a past situation — the speaker is certain that something was the case.

For example:

The monitoring network must have been damaged during the seismic event — the data stream stopped at precisely the moment the tremor was recorded. The samples must have been contaminated at some point during the collection process — the readings are inconsistent with everything else in the data set.

C. Should Be and Should Have Been

Should be — advice, recommendation, and expectation in the passive

Should be + past participle expresses advice, recommendation, or expectation about a present or future action.

For example:

Research findings should be submitted for peer review before they are communicated to policymakers or the general public. All instruments should be checked and recalibrated at the start of each field season to ensure the continuity and reliability of the monitoring data. The results should be interpreted with caution given the relatively small sample size and the limited temporal scope of the study.

Should have been — unfulfilled past obligation or expectation in the passive

Should have been + past participle expresses that something was required or expected but was not done — regret or criticism in the passive voice.

For example:

Comprehensive baseline measurements should have been established before the extraction operations were permitted to begin — the failure to require them represents a serious regulatory oversight. The preliminary findings should have been submitted for independent verification before they were communicated to the press — the breach of protocol has undermined their credibility.

Should not have been — criticism of a past action in the passive

Should not have been + past participle expresses that something was done that should not have been.

For example:

The data should not have been released before the peer review process was complete — the premature publication has created significant confusion in the scientific community. The site should not have been disturbed during the nesting season — the damage to the ecosystem may be irreversible.

D. Can Be and Could Be

Can be — present possibility or ability in the passive

Can be + past participle expresses that something is possible or capable of being done — often describing what is technically feasible.

For example:

Deep-sea sediment cores can be analysed to reconstruct climate conditions going back hundreds of thousands of years. Concentrations of dissolved methane as low as one part per billion can be detected using the latest generation of sensors. The full extent of the vent field can be mapped using a combination of acoustic sonar and optical imaging systems.

Could be — tentative possibility or hypothetical in the passive

Could be + past participle expresses tentative possibility — what might be possible or what would be possible under certain conditions.

For example:

The anomalous readings could be explained by a temporary malfunction in the sensor array rather than by a genuine change in conditions. If additional funding were secured, the monitoring network could be extended to cover the entire southern sector of the vent field. The species could be classified as critically endangered if the current rate of habitat loss continues.

Could have been — past possibility or past ability not used in the passive

Could have been + past participle expresses either a past possibility (something that might have happened) or past ability that was not used (something that could have been done but was not).

For example:

The damage could have been avoided if a more comprehensive environmental impact assessment had been conducted before the operations began. Baseline measurements could have been established decades earlier if the necessary regulatory framework had been in place. The anomaly could have been caused by instrument drift — further investigation is needed to determine the exact source.

E. May Be and Might Be

May be — present or future possibility in the passive

May be + past participle expresses genuine possibility — something that is possible but not certain.

For example:

The species may be classified as critically endangered following the publication of the survey results. The findings may be affected by seasonal variation in the conditions of the vent field — a limitation that is acknowledged in the methodology section. The data may be made available to other research institutions once the initial analysis has been completed and the results published.

Might be — weaker possibility in the passive

Might be + past participle expresses a lower degree of certainty than may be — a more tentative assessment of what is possible.

For example:

The anomalous readings might be explained by a previously undetected geological feature in the vicinity of the monitoring station. The species might be found at greater depths than previously assumed — the sampling methodology of the original survey may not have been sensitive enough to detect it.

May have been and might have been — past possibility in the passive

May have been and might have been + past participle express past possibility — what might have been the case in the past.

For example:

The early warning signs may have been missed because the monitoring network was not sufficiently comprehensive at that time. The species might have been present in the ecosystem long before the first systematic survey was conducted — the sampling methodology was simply not sensitive enough to detect it.

F. Will Be and Would Be

Will be — future necessity or certainty in the passive

Will be + past participle expresses a certain or strongly predicted future action in the passive voice.

For example:

The findings will be submitted for peer review before the end of the month and are expected to be published in a leading journal by the spring. New monitoring stations will be installed across the southern sector during the next expedition, significantly extending the spatial coverage of the network. The results will be made available to the broader scientific community once the embargo period has expired.

Would be — conditional or hypothetical in the passive

Would be + past participle expresses a conditional or hypothetical future action — what would happen if certain conditions were met.

For example:

If additional funding were secured, the monitoring network would be extended to cover the entire Indian Ocean basin. If the data were analysed using a more sophisticated statistical approach, the underlying pattern would be revealed more clearly. A more comprehensive environmental impact assessment would have been required if the regulatory framework had been properly implemented.

Would have been — hypothetical past consequence in the passive

Would have been + past participle expresses what would have happened in the past if conditions had been different — the third conditional in the passive.

For example:

If baseline measurements had been established before the operations began, the full extent of the damage would have been quantified far more accurately. If the early warning signs had been recognised and acted upon, many of the affected ecosystems would have been protected before irreversible damage was done.

G. Shall Be — Formal Obligation in the Passive

Shall be + past participle expresses formal, legal, and institutional obligation — what is mandated or required by law, regulation, or official agreement.

For example:

All data shall be submitted to the central archive in the prescribed format within thirty days of collection. No samples shall be removed from the controlled environment without the prior written consent of the principal investigator. The findings shall be made available to the international scientific community within twelve months of the completion of the survey.

This use of shall be is characteristic of legal documents, contracts, international treaties, and institutional regulations — where it carries the force of a formal requirement.

H. Ought To Be and Ought To Have Been

Ought to be — moral obligation or logical expectation in the passive

Ought to be + past participle expresses moral obligation or logical expectation — slightly more emphatic than should be in its moral weight.

For example:

The benefits of deep-sea mineral extraction ought to be distributed equitably among the communities most affected by its environmental consequences. The data ought to be made freely available to the international scientific community — it was collected using public funding and should not be subject to commercial restrictions.

Ought to have been — unfulfilled past moral obligation in the passive

Ought to have been + past participle expresses that something was morally right or expected but was not done — more emphatic than should have been.

For example:

A comprehensive regulatory framework for deep-sea mining ought to have been established long before extraction operations reached their current scale. The risks of the proposed methodology ought to have been communicated to all members of the team before the expedition departed — the failure to do so was a serious breach of duty.

I. Need To Be and Needn’t Be

Need to be — necessity in the passive

Need to be + past participle expresses that something is necessary — what needs to be done.

For example:

The instruments need to be recalibrated after every three dives to maintain the accuracy of the data. The full implications of the findings need to be considered carefully before any policy decisions are made. The methodology needs to be revised before the study can be replicated by independent teams.

Needn’t be — absence of necessity in the passive

Needn’t be + past participle expresses that something is not necessary — it does not need to be done.

For example:

The full data set needn’t be submitted until the analysis has been completed and the results verified. Every sample needn’t be analysed individually — a representative subset is sufficient for the purposes of the preliminary study.

J. Had Better Be — Urgent Necessity in the Passive

Had better be + past participle expresses urgent necessity with an implicit warning — something must be done now or negative consequences will follow.

For example:

The funding application had better be submitted before midnight — there is absolutely no possibility of an extension. The data had better be backed up before the system undergoes the scheduled maintenance — a failure during the update could result in permanent loss.

3. Usage in Context

• Must be + past participle expresses strong necessity or logical certainty in the passive — used in formal instructions, regulations, and logical deductions.

All samples must be stored at a constant temperature of −20°C from the point of collection until they arrive at the laboratory for analysis. The anomalous readings must be caused by a malfunction in the sensor — no natural process could produce a temperature gradient of this magnitude.

• Must have been + past participle expresses confident past logical deduction — the speaker is certain that something was the case in the past.

The monitoring network must have been damaged during the seismic event — the data stream ceased at the precise moment the tremor was recorded by the seismological stations. The samples must have been contaminated at some stage during the collection or storage process — the chemical signature is inconsistent with every other reading in the data set.

• Should be + past participle expresses advice, recommendation, and expectation in the passive — what is recommended or expected.

Research findings should be submitted for independent peer review before they are communicated to policymakers, the media, or the general public. The results should be interpreted with appropriate caution given the limitations of the methodology and the relatively small sample size of the current study.

• Should have been + past participle expresses that something was obligatory or expected but was not done — regret or criticism in the passive.

Comprehensive baseline measurements of the ecosystem should have been established before the extraction operations were permitted to begin. The preliminary findings should have been independently verified before they were presented at the international conference.

• Can be + past participle expresses present possibility or technical capability — what is possible or feasible.

Deep-sea sediment cores can be analysed to reconstruct climate conditions going back hundreds of thousands of years with remarkable precision. The full extent of the vent field can be mapped using a combination of acoustic sonar imaging and high-resolution optical surveys from autonomous underwater vehicles.

• Could be + past participle expresses tentative possibility or hypothetical capability in the passive.

The anomalous readings could be explained by a previously undetected geological feature in the vicinity of the monitoring station. If additional funding were secured, the monitoring network could be extended to cover the entire southern sector of the Indian Ocean basin.

• Could have been + past participle expresses past possibility or missed opportunity in the passive.

The damage to the ecosystem could have been avoided if a more rigorous environmental impact assessment had been conducted before the extraction operations were authorised. Baseline measurements of the vent community could have been established decades earlier if the necessary regulatory framework and financial resources had been made available.

• May be + past participle expresses genuine present or future possibility in the passive.

The species may be classified as critically endangered following the publication of the survey results and the formal assessment by the international conservation committee. The data may be made available to other research institutions once the initial analysis has been completed and the preliminary findings have been published.

• Might be + past participle expresses weaker or more tentative possibility in the passive.

The anomalous readings might be explained by instrument drift rather than by a genuine change in the underlying conditions of the vent field. The species might be found at considerably greater depths than previously assumed — the original survey methodology may not have been sensitive enough to detect it.

• May have been and might have been + past participle express past possibility in the passive.

The early warning signs of the ecological shift may have been missed because the monitoring network was not sufficiently dense to detect localised changes. Some of the data inconsistencies might have been introduced during the processing stage rather than at the point of original collection.

• Will be + past participle expresses certain or strongly predicted future actions in the passive.

The findings will be submitted for peer review before the end of the month and are expected to be published in a leading international journal by the spring of next year. New monitoring stations will be installed across the southern sector of the vent field during the next expedition, extending the spatial coverage of the network significantly.

• Would be + past participle expresses conditional or hypothetical future actions in the passive.

If additional funding were secured, the survey would be extended to cover the full extent of the southern Indian Ocean basin. If the data were re-analysed using a more sophisticated statistical approach, the underlying pattern would be revealed far more clearly.

• Would have been + past participle expresses hypothetical past consequences in the passive — the third conditional in passive form.

If baseline measurements had been established before the operations began, the full extent of the environmental damage would have been quantified far more accurately. If the early warning signs had been recognised and acted upon promptly, many of the most severely affected ecosystems would have been protected before irreversible damage was done.

• Shall be + past participle expresses formal legal and institutional obligation — used in contracts, treaties, and official regulations.

All expedition members shall be provided with a full safety briefing before departure and shall be required to sign a declaration confirming their understanding of the protocols. The data shall be submitted to the central archive in the prescribed format and shall be made available to the international scientific community within twelve months of collection.

• Ought to be + past participle expresses moral obligation or logical expectation in the passive — slightly more emphatic than should be.

The benefits of deep-sea mineral extraction ought to be distributed equitably among the communities most directly affected by its environmental consequences. The data ought to be made freely available — it was collected using public funding and should not be subject to commercial confidentiality restrictions.

• Need to be + past participle expresses necessity in the passive — what needs to be done.

The instruments need to be recalibrated after every three dives to maintain the accuracy and consistency of the monitoring data. The full implications of the findings need to be considered carefully and systematically before any policy decisions are taken on the basis of this study.

• Had better be + past participle expresses urgent necessity with an implicit warning — something must be done immediately or negative consequences will follow.

The funding application had better be submitted before midnight — the system closes at that point and there is no possibility whatsoever of a late submission being accepted. The data had better be backed up before the server maintenance begins — a system failure during the update could result in the permanent and irrecoverable loss of months of monitoring data.

• In the passive voice, modal + be + past participle is used for present and future meaning; modal + have been + past participle is used for past meaning.

The data must be archived immediately. (present/future — obligation now) The data must have been archived before the system crashed. (past — deduction about what happened)

• In formal academic and scientific writing, modal passives are used extensively to express what is required, recommended, or possible without specifying who is responsible for the action.

The methodology should be documented in sufficient detail to allow independent replication by other research teams. The limitations of the study must be acknowledged clearly in the discussion section of the paper.

4. Common Errors and Corrections

5. Lesson Mastery

After completing this lesson, you should now be able to:

    ✅ Form modal passive constructions correctly in present, future, and past forms

    ✅ Apply all major modal passives — must be, should be, can be, may be, might be, could be, will be, would be, shall be, ought to be, had better be, and need to be

    ✅ Use modal perfect passives — must have been, should have been, could have been, etc. — correctly

    ✅ Recognise and correct common errors in modal passive construction