Consider the following premises. Jennifer is a nurse. Can we infer the following from them? If we can, name the inference rule being used: There is at least one z_4 for which z_4 is a nurse or z_4 will drink water.
 From the fact that Jennifer is a nurse we can infer that there is at least one z_4 for which z_4 is a nurse via existential generalization. Finally, from the fact that there is at least one z_4 for which z_4 is a nurse we can infer that there is at least one z_4 for which z_4 is a nurse or z_4 will drink water via existential addition. Therefore, the answer is yes.