Consider the following premises. There is at least one z_2 for which if z_2 were a politician, then z_2 is making tea. For all z_2, z_2 will make tea if and only if z_2 is a politician. For all z_2, z_2 is not a politician. Can we infer the following from them? There is at least one z_2 for which z_2 will not make tea.
 From the fact that for all z_2, z_2 will make tea if and only if z_2 is a politician we can infer that for all z_2, if z_2 makes tea, then z_2 is a politician. From the fact that there is at least one z_2 for which if z_2 were a politician, then z_2 is making tea, and that for all z_2, if z_2 makes tea, then z_2 is a politician we can infer that there is at least one z_2 for which z_2 is a politician if and only if z_2 will make tea. Finally, from the fact that there is at least one z_2 for which z_2 is a politician if and only if z_2 will make tea, and that for all z_2, z_2 is not a politician we can infer that there is at least one z_2 for which z_2 will not make tea. Therefore, the answer is yes.