Consider the following premises. Barbara is not a scientist. For all z_2, if z_2 climbs a mountain, then z_2 is curious. David is curious if and only if Barbara is a scientist. Can we infer the following from them? David is climbing a mountain.
 From the fact that for all z_2, if z_2 climbs a mountain, then z_2 is curious we can infer that if David climbs a mountain, then David is curious. From the fact that David is curious if and only if Barbara is a scientist, and that Barbara is not a scientist we can infer that David is not curious. Finally, from the fact that if David climbs a mountain, then David is curious, and that David is not curious we can infer that David is not climbing a mountain, which contradicts that David is climbing a mountain. Therefore, the answer is no.