How to use "imagining" in a sentence

He looked about him but, seeing no one, he started to walk away, thinking that he was imagining things.

This time she hadn't been imagining a threat

At first Vivienne thought that, she was imagining the change in temperature, but the closer she drew to the end of the corridor, the colder it got

I cried softly, imagining some horrible re-arrangement of Andre's face - perhaps his eyes where his ears should be, or his mouth at the back of his neck