Consider the following premises. For all x_3, x_3 will play squash. For all x_3, x_3 will not play squash or x_3 will take a plane. For all x_3, x_3 is not a scientist. Can we infer the following from them? If we can, name the inference rule being used: There is at least one x_3 for which x_3 will not take a plane.
 From the fact that for all x_3, x_3 will play squash we can infer that for all x_3, x_3 will play squash or x_3 is a scientist via universal addition. From the fact that for all x_3, x_3 will play squash or x_3 is a scientist, and that for all x_3, x_3 will not play squash or x_3 will take a plane we can infer that for all x_3, x_3 is a scientist or x_3 will take a plane via universal resolution. Finally, from the fact that for all x_3, x_3 is a scientist or x_3 will take a plane, and that for all x_3, x_3 is not a scientist we can infer that for all x_3, x_3 will take a plane via universal disjunctive syllogism, which contradicts that There is at least one x_3 for which x_3 will not take a plane. Therefore, the answer is no.