- there exist A's that are also B.... which are not also C's which are D.... there exist females that are also human, but which at the same time are not living x-ray vision-endowed beings... that doesn't contradict the statement that all females are living things (All A's are C)... I can truthfully say that I'm not a living thing with x-ray vision... I can also truthfully say that I'm a living thing. This involves the notions that an "AND" statement (C-D) is only true if both propositions involved in the conjunction are true... if one, say C, is true, while the other, say D, is false, the conjunction C-D is false. Hence, I can say NOT 'C-D' while still truthfully asserting C
I think this is where the question lays the trap, and hence, why people get confused.