Consider the following premises. For all y, y is not an electrician. If Patricia were a taxi driver, then Michael is drinking water. For all y, y will drink water if and only if y is an electrician. Can we infer the following from them? If we can, name the inference rule being used: Patricia is a taxi driver.
 From the fact that for all y, y will drink water if and only if y is an electrician, and that for all y, y is not an electrician we can infer that for all y, y will not drink water via universal biconditional elimination. From the fact that for all y, y will not drink water we can infer that Michael is not drinking water via universal instantiation. Finally, from the fact that if Patricia were a taxi driver, then Michael is drinking water, and that Michael is not drinking water we can infer that Patricia is not a taxi driver via modus tollens, which contradicts that Patricia is a taxi driver. Therefore, the answer is no.