Consider the following premises. For all x_14, x_14 is curious. Susan is playing a game or it is cloudy. For all x_14, if x_14 takes a plane, then x_14 is playing a game. For all x_14, if x_14 plays a game, then x_14 is taking a plane. For all x_14, if x_14 takes a plane, then x_14 is not curious. Can we infer the following from them? If we can, name the inference rule being used: It is cloudy.
 From the fact that for all x_14, if x_14 takes a plane, then x_14 is playing a game, and that for all x_14, if x_14 plays a game, then x_14 is taking a plane we can infer that for all x_14, x_14 will take a plane if and only if x_14 will play a game via universal biconditional introduction. From the fact that for all x_14, if x_14 takes a plane, then x_14 is not curious, and that for all x_14, x_14 is curious we can infer that for all x_14, x_14 will not take a plane via universal modus tollens. From the fact that for all x_14, x_14 will take a plane if and only if x_14 will play a game, and that for all x_14, x_14 will not take a plane we can infer that for all x_14, x_14 will not play a game via universal biconditional elimination. From the fact that for all x_14, x_14 will not play a game we can infer that Susan is not playing a game via universal instantiation. Finally, from the fact that Susan is playing a game or it is cloudy, and that Susan is not playing a game we can infer that it is cloudy via disjunctive syllogism. Therefore, the answer is yes.