Consider the following premises. For all x_7, x_7 will play tennis if and only if x_7 will play squash. There is at least one x_7 for which if x_7 plays squash, then x_7 is a janitor. For all x_7, x_7 will climb a mountain or x_7 will play tennis. For all x_7, if x_7 climbs a mountain, then x_7 is playing squash. Can we infer the following from them? For all x_7, x_7 is not a janitor.
 From the fact that for all x_7, x_7 will play tennis if and only if x_7 will play squash we can infer that for all x_7, if x_7 plays tennis, then x_7 is playing squash. From the fact that for all x_7, if x_7 climbs a mountain, then x_7 is playing squash, that for all x_7, if x_7 plays tennis, then x_7 is playing squash, and that for all x_7, x_7 will climb a mountain or x_7 will play tennis we can infer that for all x_7, x_7 will play squash. Finally, from the fact that there is at least one x_7 for which if x_7 plays squash, then x_7 is a janitor, and that for all x_7, x_7 will play squash we can infer that there is at least one x_7 for which x_7 is a janitor, which contradicts that For all x_7, x_7 is not a janitor. Therefore, the answer is no.