Modals of speculation (present & past)
Modalsmust = I'm sure it's true. might / may / could = it's possible. can't = I'm sure it's not true. Add 'have + participle' for the past.
Deduce: 'His car isn't here.' (sure he left)
Deduce: 'She's fluent at nine years old.' (impossible she studied 20 years)
