Consider the following premises. There is at least one x_12 for which x_12 is an office clerk. For all x_12, x_12 is an office clerk if and only if x_12 will climb a mountain. For all x_12, x_12 is a bartender. Can we infer the following from them? Some bartenders will climb a mountain.
 From the fact that for all x_12, x_12 is an office clerk if and only if x_12 will climb a mountain we can infer that for all x_12, if x_12 were an office clerk, then x_12 is climbing a mountain. From the fact that for all x_12, if x_12 were an office clerk, then x_12 is climbing a mountain, and that there is at least one x_12 for which x_12 is an office clerk we can infer that there is at least one x_12 for which x_12 will climb a mountain. Finally, from the fact that for all x_12, x_12 is a bartender, and that there is at least one x_12 for which x_12 will climb a mountain we can infer that some bartenders will climb a mountain. Therefore, the answer is yes.