Consider the following premises. For all x_7, if x_7 were a doctor, then x_7 is a cashier. For all x_7, x_7 is a carpenter. For all x_7, x_7 is a doctor and x_7 is a taxi driver. Can we infer the following from them? There is at least one x_7 for which either x_7 is a cashier or x_7 is a carpenter are not true.
 From the fact that for all x_7, x_7 is a doctor and x_7 is a taxi driver we can infer that for all x_7, x_7 is a doctor. From the fact that for all x_7, if x_7 were a doctor, then x_7 is a cashier, and that for all x_7, x_7 is a doctor we can infer that for all x_7, x_7 is a cashier. Finally, from the fact that for all x_7, x_7 is a cashier, and that for all x_7, x_7 is a carpenter we can infer that for all x_7, x_7 is a cashier and x_7 is a carpenter, which contradicts that There is at least one x_7 for which either x_7 is a cashier or x_7 is a carpenter are not true. Therefore, the answer is no.