I should / must
'deber' is slightly more formal than 'tener que'. Can express strong obligation or mild suggestion.
I should / must study more.
I should call the doctor to make an appointment.
—Are you coming to the party? —I do not know, I need to finish some work first.
I should call the doctor to make an appointment.
—Are you coming to the party? —I do not know, I need to finish some work first.