Consider the following premises. There is at least one x_3 for which if x_3 were a soldier, then x_3 is not a doctor. For all x_3, x_3 is a doctor and x_3 is a taxi driver. Can we infer the following from them? For all x_3, x_3 is a soldier.
 From the fact that for all x_3, x_3 is a doctor and x_3 is a taxi driver we can infer that for all x_3, x_3 is a doctor. Finally, from the fact that there is at least one x_3 for which if x_3 were a soldier, then x_3 is not a doctor, and that for all x_3, x_3 is a doctor we can infer that there is at least one x_3 for which x_3 is not a soldier, which contradicts that For all x_3, x_3 is a soldier. Therefore, the answer is no.