Deduction, obligation, and modals with the perfect: must have, should have, could have. · about 14 minutes
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What is it? Modals can do more than ask permission. They show how sure you are (must be, can't be, might be), express obligation (have to, mustn't), and - with have + past participle - talk about the past: should have studied, could have won.
Why does it matter? These forms let you reason, advise, criticise and regret precisely - skills you need in discussions, essays and exams.
Where do we use it? "He must be at home - his lights are on." "You should have called me." "We needn't have hurried."
In this lesson you will:
