Consider the following premises. For all x_6, x_6 will drink water. For all x_6, if x_6 were a cashier, then x_6 is a nurse. For all x_6, x_6 is a cashier or x_6 is a doctor. For all x_6, x_6 is a nurse or x_6 is not a doctor. Can we infer the following from them? There is at least one x_6 for which either x_6 is a nurse or x_6 will drink water are not true.
 From the fact that for all x_6, x_6 is a nurse or x_6 is not a doctor we can infer that for all x_6, if x_6 were a doctor, then x_6 is a nurse. From the fact that for all x_6, if x_6 were a cashier, then x_6 is a nurse, that for all x_6, if x_6 were a doctor, then x_6 is a nurse, and that for all x_6, x_6 is a cashier or x_6 is a doctor we can infer that for all x_6, x_6 is a nurse. Finally, from the fact that for all x_6, x_6 is a nurse, and that for all x_6, x_6 will drink water we can infer that for all x_6, x_6 is a nurse and x_6 will drink water, which contradicts that There is at least one x_6 for which either x_6 is a nurse or x_6 will drink water are not true. Therefore, the answer is no.