You can see yourself that this is to die almost at the moment one is born; our existence is a point, our lifespan an instant, our planet an atom.
A man within a gnat, with the lifespan of a day, would feel subjectively that he had lived a lifetime within it, although only those same forty minutes would pass by until his return to his own body, helmeted upon the couch.
By his own time-sense, warped by the lifespan of his host, he felt he'd been present in that room well over an hour.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "lifespan" in a variety of sentences. We hope that you will now be able to make sentences using this word.
