Modal Verbs and Possibility
Understand and use modal verbs (can, may, must, might, shall, will, could, should, would) and modal adverbs (perhaps, surely, certainly) to indicate degrees of possibility, necessity, and permission
What a learner can do afterwards
- Select a modal verb to express certainty, probability, or possibility in a sentence, e.g. 'It will rain' vs 'It might rain' vs 'It could rain'
- Replace a modal verb with a modal adverb to achieve a similar effect, e.g. 'He might come' → 'Perhaps he will come'
- Distinguish between modals expressing permission (may, can), obligation (must, should), and possibility (might, could) in context
1 · Read
Modal verbs are small helper words like can, may, must, might, could, should, would, shall, and will. They sit before another verb and change how sure, allowed, or needed something is.
Zara checks the sky and says three things. "It will rain" means she is sure. "It might rain" means she thinks it is possible. "It could rain" also means possible, but she still is not certain either way.
A school sign says, "Students may leave early on Fridays." That means students are allowed to leave, but do not have to. Another sign says, "Students must wear a badge." That means wearing a badge is required.
Modal verbs can also give advice or offer an idea. 'Should' gives advice: 'You should rest after a long run.' 'Could' offers an idea: 'We could try the new bakery.' 'Shall we' offers to do something together: 'Shall we sit by the window?' Advice is a good idea, not a strict rule like 'must'.
Add 'not' to a modal verb to flip its meaning. 'You must not feed the birds' is a rule against feeding them. 'It can't be midnight' says midnight is not possible. Modal adverbs have strengths too: 'perhaps' is unsure, while 'surely' and 'certainly' are almost completely sure.
You can often swap a modal verb for a modal adverb and keep the same meaning. "He might come" becomes "Perhaps he will come."
Modal verbs and modal adverbs both show how sure, allowed, or required something is, so choose the one that matches what you mean.
More to read
Modal verbs
What are modal verbs?
Modal verbs are helper words that sit in front of a main verb and change its meaning. Words like might, must, can, could, should, will, and would are modal verbs. They tell us if someone is able to do something, is allowed to do something, needs to do something, or if something is only possible.
Modal verbs can change what a sentence means in big ways. Look at this sentence: I go to Jenna's birthday party. Now add a modal verb. I can go to Jenna's party means I am able to go. I might go means maybe I will go, maybe I will not. I must go means I really have to go. I should go means going is a good idea. One little word changes everything!
Some modal verbs show how sure we are. It will rain means you are certain. It might rain means it is only possible. It could rain means there is a chance, but you are not sure.
We can also use special adverbs to show possibility. Words like perhaps, surely, and certainly work in a similar way. He might come means nearly the same thing as Perhaps he will come.
Modal verbs also show permission and rules. May I have some juice asks politely for permission. You must wear a helmet states a rule. So when you read or write, listen for these little helper words.
2 · Watch
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Where it sits
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