Consider the following premises. If it is overcast, then Mary is playing tennis. It is not overcast. For all z, z will play tennis if and only if z will take a plane. If Mary plays tennis, then it is overcast. Can we infer the following from them? Mary is taking a plane.
 From the fact that for all z, z will play tennis if and only if z will take a plane we can infer that Mary is playing tennis if and only if Mary is taking a plane. From the fact that if Mary plays tennis, then it is overcast, and that if it is overcast, then Mary is playing tennis we can infer that Mary is playing tennis if and only if it is overcast. From the fact that Mary is playing tennis if and only if it is overcast, and that it is not overcast we can infer that Mary is not playing tennis. Finally, from the fact that Mary is playing tennis if and only if Mary is taking a plane, and that Mary is not playing tennis we can infer that Mary is not taking a plane, which contradicts that Mary is taking a plane. Therefore, the answer is no.