Consider the following premises. It is raining. It is raining if and only if Charles is climbing a mountain. If Charles climbs a mountain, then Susan is playing tennis. Can we infer the following from them? Susan is not playing tennis.
 From the fact that it is raining if and only if Charles is climbing a mountain we can infer that if it rains, then Charles is climbing a mountain. From the fact that if it rains, then Charles is climbing a mountain, and that it is raining we can infer that Charles is climbing a mountain. Finally, from the fact that if Charles climbs a mountain, then Susan is playing tennis, and that Charles is climbing a mountain we can infer that Susan is playing tennis, which contradicts that Susan is not playing tennis. Therefore, the answer is no.