Or shall I do my plain duty as a citizen?

They had come up against simple need and acted in plain duty.

To do this, citizens should be pressed to political involvement as a matter of plain duty.

"I think it is my plain duty to throw in my lot with them and minister to their souls", he wrote.

That man ought to have been in his bed, resting, and my plain duty was to send him there.

A plain social duty lies before him, which he performs correctly, but without the least enthusiasm.

If the Plan needs to learn the secret of the jetiess drive, that's my plain duty.

If you do know of anyone who might have done it, it's your plain duty to talk about it to me!

For see you, if they have souls, then it is our plain duty to win them to the Faith.

His plain duty was to keep the peace.