Consider the following premises. For all x_10, x_10 is curious. There is at least one x_10 for which x_10 is an electrician if and only if x_10 is curious. For all x_10, if x_10 were an electrician, then x_10 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_10 for which x_10 is a soldier.
 From the fact that there is at least one x_10 for which x_10 is an electrician if and only if x_10 is curious we can infer that there is at least one x_10 for which if x_10 were curious, then x_10 is an electrician via existential biconditional elimination. From the fact that there is at least one x_10 for which if x_10 were curious, then x_10 is an electrician, and that for all x_10, if x_10 were an electrician, then x_10 is a soldier we can infer that there is at least one x_10 for which if x_10 were curious, then x_10 is a soldier via existential transitivity. Finally, from the fact that there is at least one x_10 for which if x_10 were curious, then x_10 is a soldier, and that for all x_10, x_10 is curious we can infer that there is at least one x_10 for which x_10 is a soldier via existential modus ponens. Therefore, the answer is yes.