Modals of Deduction (Present)
These modals express how certain we are about a present situation based on evidence. 'Must' shows near-certainty, 'might/may/could' show possibility, and 'can't' shows we are sure something is impossible.
Level B1
Modals
Summary
- These modals express how certain we are about a present situation based on evidence. 'Must' shows near-certainty, 'might/may/could' show possibility, and 'can't' shows we are sure something is impossible.
Structure
must / might / may / could / can't + base verb (+ be + -ing)
Examples
- She must be exhausted after that flight.
- He might be at the gym; he usually goes on Tuesdays.
- That can't be the right answer.
- They could be stuck in traffic right now.
Common mistakes
- • Using 'mustn't' for negative deduction: 'He mustn't be home' should be 'He can't be home'.
- • Using 'don't have to' for impossibility instead of 'can't'.
Related
More modals
Can / Could (Ability and Permission)
A2
Use 'can' for present ability and informal permission or requests. Use 'could' for past ability and for more polite requests.
Must / Have To (Obligation)
B1
Use 'must' and 'have to' to express obligation or necessity. 'Mustn't' means something is forbidden, while 'don't have to' means there is no obligation.
May / Might (Possibility)
B1
Use 'may' and 'might' to talk about present or future possibility. 'May' is also used for formal permission.
Would for Past Habits
B2
Use 'would' to talk about repeated past actions and habits, similar to 'used to'. Unlike 'used to', 'would' is not normally used for past states.
Would (Polite Requests and Hypotheticals)
B1
Use 'would' for polite requests and offers, for hypothetical results (especially in conditionals), and to describe imagined situations.
Can and Can't for Ability
A1
Use 'can' to say someone is able to do something and 'can't' for inability. 'Can' is followed by the base form of the verb and stays the same for all subjects.