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