Consider the following premises. For all z, if z were a soldier, then z is not drinking water. There is at least one z for which z is bored if and only if z is a soldier. For all z, z will drink water. Can we infer the following from them? If we can, name the inference rule being used: For all z, z is bored.
 From the fact that there is at least one z for which z is bored if and only if z is a soldier we can infer that there is at least one z for which if z were bored, then z is a soldier via existential biconditional elimination. From the fact that for all z, if z were a soldier, then z is not drinking water, and that for all z, z will drink water we can infer that for all z, z is not a soldier via universal modus tollens. Finally, from the fact that there is at least one z for which if z were bored, then z is a soldier, and that for all z, z is not a soldier we can infer that there is at least one z for which z is not bored via existential modus tollens, which contradicts that For all z, z is bored. Therefore, the answer is no.