Consider the following premises. For all z, if z makes tea, then z is taking a plane. There is at least one z for which z will take a plane or z is a scientist. For all z, z will not make tea. For all z, if z takes a plane, then z is making tea. Can we infer the following from them? If we can, name the inference rule being used: For all z, z is not a scientist.
 From the fact that for all z, if z makes tea, then z is taking a plane, and that for all z, if z takes a plane, then z is making tea we can infer that for all z, z will make tea if and only if z will take a plane via universal biconditional introduction. From the fact that for all z, z will make tea if and only if z will take a plane, and that for all z, z will not make tea we can infer that for all z, z will not take a plane via universal biconditional elimination. Finally, from the fact that there is at least one z for which z will take a plane or z is a scientist, and that for all z, z will not take a plane we can infer that there is at least one z for which z is a scientist via existential disjunctive syllogism, which contradicts that For all z, z is not a scientist. Therefore, the answer is no.