Answer:
Liza: May I have a look at it? (Permission)
David: I can't think who it’s from. (Negative ability)
Liza: It might be important. (Assumption)
David: Can you read the postmark? (Ability)
Liza: It could be from your bank manager (possibility), so you should open it immediately. (Advice)
Explanation:
Modal verbs are a type of auxiliary (helping) verb used to indicate modality, meaning they are used to show likelihood, obligation, ability, suggestions, order, capability or advice.
As shown above: