另证 P(ABC)=P(C-AB)=P(C-CAB) P(C)-P(C AB) P(C)-P(C-AB) 2P(C)-[P(C)-P(AB) =P(AB)=0 因为题中并未设ABcC= P(C) − P(C AB) = P(C) −[ P(C) − P(AB)] = P(AB) = 0. = P(C) − P(C − AB) P(ABC) = P(C − AB) = P(C −C AB) 另证 ? 因为题中并未设 AB  C