Consider the following premises. There is at least one x_4 for which x_4 is a police officer. For all x_4, if x_4 were a mechanic, then x_4 is taking a plane. For all x_4, if x_4 plays tennis, then x_4 is taking a plane. For all x_4, x_4 is not a police officer or x_4 is a mechanic. Can we infer the following from them? There is at least one x_4 for which x_4 will take a plane.
 From the fact that there is at least one x_4 for which x_4 is a police officer we can infer that there is at least one x_4 for which x_4 is a police officer or x_4 will play tennis. From the fact that there is at least one x_4 for which x_4 is a police officer or x_4 will play tennis, and that for all x_4, x_4 is not a police officer or x_4 is a mechanic we can infer that there is at least one x_4 for which x_4 will play tennis or x_4 is a mechanic. Finally, from the fact that for all x_4, if x_4 plays tennis, then x_4 is taking a plane, that for all x_4, if x_4 were a mechanic, then x_4 is taking a plane, and that there is at least one x_4 for which x_4 will play tennis or x_4 is a mechanic we can infer that there is at least one x_4 for which x_4 will take a plane. Therefore, the answer is yes.