The point is, my young friend, that we have certain duties, not in respect of others, but ourselves.

In one minute I must concern myself with certain important duties.

The agents were assigned to certain duties immediately upon arrival.

"To preserve the order, he assigned each god certain duties and powers."

"Godslayer," for example, involved certain duties which were not likely to come up very often.

If there's a lord at all, he owes him certain duties and no more.

Each man seemed to have certain duties to perform, which were his own particular business.

"Assuming this were true, you understand that I have certain duties to perform."

We have certain vital duties to perform; to ourselves, to the outside world, and to Science.

You can get into a dangerous situation when certain duties are delegated to less senior staff members who do not have enough experience.