Still the thought of the swans persisted in his mind and he kept walking.

He tried not to listen, but the thought persisted.

But the driving thought persisted: I've got to get away!

Still, the thought persisted: Why hadn't they just killed him?

But the thought persisted: this thing inside of which he had been thrust was similar to a tree.

A single thought persisted in the back of his mind.

The thought persisted, uncertain of itself: this couldn't be on government level.

And why do thoughts about the sea Persist in coming to his mind?

Yet in the back of his mind the thought persisted that somebody out there was frantically yelling for help.

But at the back of my mind the thought persisted that the odds would be still more favorable if Michael were the father.