Consider the following premises. Thomas is a nurse if and only if Charles is driving a car. For all x, x will not drive a car. Can we infer the following from them? If we can, name the inference rule being used: Thomas is a nurse.
 From the fact that for all x, x will not drive a car we can infer that Charles is not driving a car via universal instantiation. Finally, from the fact that Thomas is a nurse if and only if Charles is driving a car, and that Charles is not driving a car we can infer that Thomas is not a nurse via biconditional elimination, which contradicts that Thomas is a nurse. Therefore, the answer is no.