Modal Verbs of Deduction
MUST, MIGHT and CAN'T
Look at her teeth! She must be a vampire.
Be careful. She might be hungry.
She can't be a vampire - they don't exist!
Note: We never use "can" or "mustn't" with this meaning - only "must" and "can't".
|MUST||I'm very sure||She must be a vampire.|
|I think it's possible||She might be hungry.|
She could be hungry.
|CAN'T||It's impossible||She can't be a vampire.|
Modal verbs are always followed by the infinitive (without 'to'). But you need to decide if you are talking about a state, an action in progress, or a finished action/state.
He might be at home now.
|modal + infinitive|
|Actions in progress now
He might be working now.
|modal + be + verb-ing|
He might have gone out.
|modal + have + past participle|
If you can't remember the difference between actions and states, you can read more about it on my state verbs pages.
Practice these modal verbs