duty / exercise, assignment (set for homework)

must, to have to, should (as a requirement) / must, to do or have with certainty / to owe (money, obligation and etc) / (even) though it be necessary (+ infinitive) / to have a duty to

test, examination

written test

duty of remembrance, duty never to forget, obligation to remember

duty calls (I gotta go, I have something to do)

(law) duty of care (legal obligation imposed on an individual requiring that they adhere to a standard of reasonable care while performing any acts that could foreseeably harm others)

to owe (someone) one [+ à (object)]

feeling of accomplishment, feeling of having accomplished one's duty, satisfaction of having seen something through

to make it one's duty to do something, to make a point of doing something, to commit to do something, to set out to do something