All these sentences use the word "so" correctly except: Flies breathe through holes in their abdomen or thorax. So do bees. Flies breathe through holes in their abdomen or thorax, so do bees. Flies breathe through holes in their abdomen or thorax; so do bees. Flies breathe through holes in their abdomen or thorax, and so do bees.
All these sentences use the word "so" correctly except "Flies breathe through holes in
their abdomen or thorax, so do bees." So should either begin a new sentence of be preceded by "and".
