Modal verbs: how you grade certainty and soften a claim.
Modals (can, could, may, might, must, should, would) do two jobs the test rewards heavily: they set the degree of certainty, and they let you make a careful, qualified claim instead of a sweeping one. Overclaiming where a quiet may belongs is one of the clearest Band 6 tells in Task 2 and Part 3.
Why this matters. Strong answers do not shout. “Technology will destroy jobs” is a Band 6 overclaim; “technology may displace some jobs” is the hedged, defensible version an examiner rewards. Modals are how you do that, and how you speculate (“it must have begun earlier”), advise (“governments should”) and grade possibility (“might” vs “must” vs “can’t”). A few simple rules (no to, no doubling, must have not must of) keep them accurate.
One small word sets the certainty, the obligation, or the caution.
Modals come before the base verb with no to (she might go, not she might to go), they do not add -s in the third person (he must, not he musts), and you cannot stack two of them.
Possibility & certainty
must · might / could / may · can't
Grade how sure you are: must (certain), might / could / may (possible), can't (impossible).
Demand is huge, so it must be expensive; that can't be the only reason.
Obligation & advice
must / have to · should / ought to
From a firm requirement (must, have to) to a recommendation (should, ought to).
Applicants must apply by Friday, and they should keep a copy.
Hedging a claim
may · might · tend to · can
Soften a sweeping statement into a careful one. The test rewards qualified claims over absolutes.
This may be partly because young people tend to value convenience.
Modal + have + past participle
must / could / should have + done
Speculate about the past (must have risen) or note a past regret (should have studied). A clear Band 7+ form.
The figure must have risen sharply after 2010.
The errors that mark you down
Three are common and basic. No to after a core modal: “you must study”, never “must to study”. No doubling: not “she will can help”, use will be able to. And must have, not must of: the contraction must’ve only sounds like “must of”, in writing it is always must have.
What modal control reads like at each band.
At Band 5
A few basic modals (can, must, will) for ability and obligation, often with errors (must to go, can to swim). Certainty is not graded, and claims are flat and absolute. Hedging is absent, and the past modal forms (must have gone) do not appear.
At Band 6
Modals are used for basic ability and obligation (can, must), but claims are often absolute, “technology will destroy jobs”, with little hedging. Errors appear: “must to”, “can to”, the occasional doubled modal. Certainty is not graded; everything is stated flatly.
At Band 7
A range of modals, with should, might and could used where they fit, and claims hedged when appropriate (“may”, “tend to”). The modal + have + past participle form turns up for past speculation. The odd slip survives but does not block meaning.
At Band 8+
The full range, used accurately and on purpose: fine distinctions of certainty (must vs might vs can't), natural hedging, and past modals (“the trend must have begun earlier”). The caution is built into the grammar, not added as an afterthought.
Pick the modal from what you actually mean.
Modals are a scale, not a list. Decide how sure, how obliged or how careful you want to be, then the modal follows.
| To say… | Use… | For example |
|---|---|---|
| It is certain (a deduction) | must | It must be expensive, given the demand. |
| It is impossible | can't / cannot | That can't be the only cause. |
| It is possible | may / might / could | Prices may rise next year. |
| It is necessary | must / have to | Applicants must submit by Friday. |
| It is advisable | should / ought to | Governments should invest more in skills. |
| Speculating about the past | must / might / could + have + done | The decline must have started earlier. |
| Softening a claim | may / tend to / can | Young people tend to prefer convenience. |
must vs have to. Must carries the speaker's own authority or strong view (“you must see it”); have to points to an outside rule (“I have to renew my visa”). For hypothetical would and the conditionals modals pair with, work through conditionals →
Ten to drill.
Choose the modal that fits the meaning. Press Check answers for your score and the reason behind each one. Nothing is sent anywhere.
You can list the modals. Hedging a claim and speculating about the past, on demand, is the work.
Overclaiming where a careful may belongs is a quiet Band 6 tell, in Task 2 and in Part 3, and it is hard to hear in your own speech.
In a lesson we push Part 3 questions and essay claims until the hedging and the past forms come out naturally, and I flag the overclaim the moment it appears. Lessons are £20 for fifty minutes, one to one, in proper British English; the first step is a free 25-minute introduction. This page is adapted from the grammar chapter of the forthcoming Ultimate Guide to IELTS Speaking.