Consider the following premises. For all y, y is a lawyer or y is not a police officer. For all y, if y were a taxi driver, then y is a police officer. For all y, y is a lawyer if and only if y is a taxi driver. Can we infer the following from them? For all y, if y were a police officer, then y is a taxi driver.
 From the fact that for all y, y is a lawyer or y is not a police officer we can infer that for all y, if y were a police officer, then y is a lawyer. From the fact that for all y, y is a lawyer if and only if y is a taxi driver we can infer that for all y, if y were a lawyer, then y is a taxi driver. Finally, from the fact that for all y, if y were a police officer, then y is a lawyer, and that for all y, if y were a lawyer, then y is a taxi driver we can infer that for all y, if y were a police officer, then y is a taxi driver. Therefore, the answer is yes.