Consider the following premises. For all x_6, if x_6 plays tennis, then x_6 is an office clerk. For all x_6, x_6 is curious. For all x_6, x_6 is a police officer. For all x_6, if x_6 were a police officer, then x_6 is playing tennis. Can we infer the following from them? There is at least one x_6 for which x_6 is not an office clerk.
 From the fact that for all x_6, if x_6 were a police officer, then x_6 is playing tennis, and that for all x_6, if x_6 plays tennis, then x_6 is an office clerk we can infer that for all x_6, if x_6 were a police officer, then x_6 is an office clerk. From the fact that for all x_6, if x_6 were a police officer, then x_6 is an office clerk, and that for all x_6, x_6 is a police officer we can infer that for all x_6, x_6 is an office clerk. From the fact that for all x_6, x_6 is curious, and that for all x_6, x_6 is an office clerk we can infer that for all x_6, x_6 is curious and x_6 is an office clerk. Finally, from the fact that for all x_6, x_6 is curious and x_6 is an office clerk we can infer that for all x_6, x_6 is curious, which contradicts that There is at least one x_6 for which x_6 is not an office clerk. Therefore, the answer is no.