Consider the following premises. Thomas is playing a game if and only if Charles is a nurse. It is sunny. If it is sunny, then Thomas is playing a game. Can we infer the following from them? If we can, name the inference rule being used: Charles is a nurse.
 From the fact that Thomas is playing a game if and only if Charles is a nurse we can infer that if Thomas plays a game, then Charles is a nurse via biconditional elimination. From the fact that if it is sunny, then Thomas is playing a game, and that it is sunny we can infer that Thomas is playing a game via modus ponens. Finally, from the fact that if Thomas plays a game, then Charles is a nurse, and that Thomas is playing a game we can infer that Charles is a nurse via modus ponens. Therefore, the answer is yes.