Consider the following premises. For all z_2, z_2 will climb a mountain and z_2 will write a letter. Can we infer the following from them? If we can, name the inference rule being used: Charles is not climbing a mountain.
 From the fact that for all z_2, z_2 will climb a mountain and z_2 will write a letter we can infer that Charles is climbing a mountain and Charles is writing a letter via universal instantiation. Finally, from the fact that Charles is climbing a mountain and Charles is writing a letter we can infer that Charles is climbing a mountain via simplification, which contradicts that Charles is not climbing a mountain. Therefore, the answer is no.