Usages of dever
Eu devo informar antecipadamente se precisar de faltar à entrevista amanhã.
I must inform in advance if I need to miss the interview tomorrow.
Eu devo estudar para o exame.
I must study for the exam.
Tu deves respeitar a tua hora de descanso, ou ficarás cansado durante o dia.
You must respect your rest time, or you will be tired during the day.
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