I mean they have their constitutional and separate duty to perform.

A duty to give reasons can also perform a more general function.

He had arranged to have no duties to perform on that day, and spent all of it reading the new book.

The Queen has many different duties to perform every day.

Any other duty he would have performed with less reluctance.

But before leaving his dead ship, he had one final duty to perform.

He had one last duty to perform for his old friend and sovereign, though.

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

Not while he still had one last duty to perform.

He had more sacred duties to perform with his money.