«بالضرورة كل إنسان متنفس في وقت ما لا دائما»
Necessarily every human breathes at some time, but not permanently.
The pedagogical point is the unspecified time: the sentence does not identify a particular instant, only some time at which the qualified judgment applies. The final phrase denies permanence over the entire duration.
The book also illustrates a negative first component concerning breathing at some time. The affirmative or negative label depends on the initial judgment, not on the final non-permanence clause.