In Hebrew, how is it possible to discern when to pronounce shva as /e/ or not at all? — Notes by Autumn Light

For the sake of illustration, in this answer I shall represent the shva as a colon in the middle of the word (:). There are four rules for determining whether a shva is na (‘moving’) or naḥ (‘resting’):

via In Hebrew, how is it possible to discern when to pronounce shva as /e/ or not at all? — Notes by Autumn Light