Consider the following premises. For all x_8, if x_8 were an office clerk, then x_8 is a police officer. For all x_8, x_8 is not a police officer. For all x_8, x_8 will make tea if and only if x_8 is an office clerk. For all x_8, if x_8 were a police officer, then x_8 is making tea. Can we infer the following from them? If we can, name the inference rule being used: There is at least one x_8 for which x_8 will make tea.
 From the fact that for all x_8, x_8 will make tea if and only if x_8 is an office clerk we can infer that for all x_8, if x_8 makes tea, then x_8 is an office clerk via universal biconditional elimination. From the fact that for all x_8, if x_8 makes tea, then x_8 is an office clerk, and that for all x_8, if x_8 were an office clerk, then x_8 is a police officer we can infer that for all x_8, if x_8 makes tea, then x_8 is a police officer via universal transitivity. From the fact that for all x_8, if x_8 makes tea, then x_8 is a police officer, and that for all x_8, if x_8 were a police officer, then x_8 is making tea we can infer that for all x_8, x_8 will make tea if and only if x_8 is a police officer via universal biconditional introduction. Finally, from the fact that for all x_8, x_8 will make tea if and only if x_8 is a police officer, and that for all x_8, x_8 is not a police officer we can infer that for all x_8, x_8 will not make tea via universal biconditional elimination, which contradicts that There is at least one x_8 for which x_8 will make tea. Therefore, the answer is no.