@Beth. Could you properly infer that most cars are not sedans? "Some" can include "most" right (if 99/100 cars are sedans, then "some cars are sedans" and it wouldn't be proper to infer that "most cars are not sedans")? Or am I misunderstanding? Thanks.
How are you going to figure out when to use this trick if you don't know the group 3 and group 4 words by heart already? And if you do know them, why aren't you just doing it properly?