Consider the following premises. For all x_12, x_12 will not take a plane. For all x_12, x_12 is an electrician if and only if x_12 will take a plane. For all x_12, x_12 will listen to a song or x_12 will climb a mountain. For all x_12, x_12 will listen to a song if and only if x_12 is an electrician. Can we infer the following from them? For all x_12, x_12 will climb a mountain.
 From the fact that for all x_12, x_12 is an electrician if and only if x_12 will take a plane, and that for all x_12, x_12 will not take a plane we can infer that for all x_12, x_12 is not an electrician. From the fact that for all x_12, x_12 will listen to a song if and only if x_12 is an electrician we can infer that for all x_12, if x_12 listens to a song, then x_12 is an electrician. From the fact that for all x_12, if x_12 listens to a song, then x_12 is an electrician, and that for all x_12, x_12 is not an electrician we can infer that for all x_12, x_12 will not listen to a song. Finally, from the fact that for all x_12, x_12 will listen to a song or x_12 will climb a mountain, and that for all x_12, x_12 will not listen to a song we can infer that for all x_12, x_12 will climb a mountain. Therefore, the answer is yes.