Consider the following premises. For all x_9, x_9 will take a plane. If John takes a plane, then Robert is playing a game. Can we infer the following from them? If we can, name the inference rule being used: Robert is not playing a game.
 From the fact that for all x_9, x_9 will take a plane we can infer that John is taking a plane via universal instantiation. Finally, from the fact that if John takes a plane, then Robert is playing a game, and that John is taking a plane we can infer that Robert is playing a game via modus ponens, which contradicts that Robert is not playing a game. Therefore, the answer is no.