Consider the following premises. For all x_12, x_12 is a bartender and x_12 is curious. For all x_12, x_12 is sad. There is at least one x_12 for which if x_12 were sad, then x_12 is a police officer. Can we infer the following from them? If we can, name the inference rule being used: There is at least one x_12 for which x_12 is a bartender and x_12 is a police officer.
 From the fact that for all x_12, x_12 is a bartender and x_12 is curious we can infer that for all x_12, x_12 is a bartender via universal simplification. From the fact that there is at least one x_12 for which if x_12 were sad, then x_12 is a police officer, and that for all x_12, x_12 is sad we can infer that there is at least one x_12 for which x_12 is a police officer via existential modus ponens. Finally, from the fact that for all x_12, x_12 is a bartender, and that there is at least one x_12 for which x_12 is a police officer we can infer that there is at least one x_12 for which x_12 is a bartender and x_12 is a police officer via existential conjunction. Therefore, the answer is yes.