I remember my first exposure to modal verbs: at primary school, whenever I asked the teacher ‘Can I go to the bathroom?’ the teacher would invariably reply ‘I don’t know. Can you?’ This was done to demonstrate that the polite way of making a request like this is to use the modal ‘may’, instead of ‘can’ (i.e. ‘May I go to the bathroom?’). ‘May’ indicates a request for permission as well as possibility, whereas ‘can’ generally indicates ability (e.g. ‘I can speak Catalan’).

Different meanings can be inferred from different modals. If I say ‘I can go the theatre’, it could either mean that I have the ability to go or that I have the freedom to go. However, if we say ‘I should go’, we are talking about the best course of action (though it is not an obligation – we use ‘must’ to denote an obligatory action).

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We can also use ‘could’ (not ‘can’) when talking about theoretical possibility (e.g. ‘it could be difficult to persuade her to leave her husband’), whereas we use ‘can’ when saying that something is possible and actually occurs, e.g. ‘it can be hard to deal with the loss of a loved one’.

We use ‘can’t’, not ‘couldn’t’, to say that something is impossible, e.g. ‘you can’t jump higher than a house’. We normally use the modals ‘may’, ‘might’ and ‘could’ to express possibility (‘he could be at home’) and ‘should’ or ‘ought to’ to express probability (‘I should pass the exam’). Again, however, we come up here against the Venn diagram-style complexity of modality. The modal ‘should’ can either mean ‘probably’ or ‘it is recommended’. ‘He should arrive soon’ could either mean it is probable he will arrive, or I recommend that he arrive soon. You will have to discern from the context which meaning is indicated by the modal, e.g. probability or recommendation.

Try our test to see how you fare with modal verbs.

A. Porter

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