Consider the following premises. For all x_8, if x_8 were a sailor, then x_8 is running. For all x_8, x_8 will go running if and only if x_8 will take a plane. For all x_8, x_8 is a sailor or x_8 will take a plane. There is at least one x_8 for which x_8 is a soldier. 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 go running and x_8 is a soldier.
 From the fact that for all x_8, x_8 will go running if and only if x_8 will take a plane we can infer that for all x_8, if x_8 takes a plane, then x_8 is running via universal biconditional elimination. From the fact that for all x_8, if x_8 were a sailor, then x_8 is running, that for all x_8, if x_8 takes a plane, then x_8 is running, and that for all x_8, x_8 is a sailor or x_8 will take a plane we can infer that for all x_8, x_8 will go running via universal disjunction elimination. Finally, from the fact that for all x_8, x_8 will go running, and that there is at least one x_8 for which x_8 is a soldier we can infer that there is at least one x_8 for which x_8 will go running and x_8 is a soldier via existential conjunction. Therefore, the answer is yes.