Personnel on the bridge stood to their stations, speaking little, and only when required by duty.

Missions with slim chance of success, but compelled by duty and curiosity.

An early riser, he was always at daily Mass, except when called out by imperative duty.

A full matron was not usually prone to violence, unless driven by duty or need.

"I think this is what you have meant by duty, all along; I do understand, at least this much of it."

He might come again, but never again by duty, in his role as the agent of the King.

You see then, whither, prompted by duty and the law, I steadfastly drive.

They looked more bored than anything, as though forced by duty to carry out some petty but necessary protocol.

Only an institution has, by duty and position, to see everything under the light of everyone's interest".

By duty, I needed to call the police, to tell the county attorney this information.