Consider the following premises. For all x_3, if x_3 were sad, then x_3 is a lawyer. There is at least one x_3 for which x_3 is sad or x_3 will climb a mountain. For all x_3, if x_3 climbs a mountain, then x_3 is taking a plane. For all x_3, if x_3 takes a plane, then x_3 is a lawyer. For all x_3, if x_3 were a lawyer, then x_3 is taking a plane. Can we infer the following from them? There is at least one x_3 for which x_3 will take a plane.
 From the fact that for all x_3, if x_3 takes a plane, then x_3 is a lawyer, and that for all x_3, if x_3 were a lawyer, then x_3 is taking a plane we can infer that for all x_3, x_3 will take a plane if and only if x_3 is a lawyer. From the fact that for all x_3, x_3 will take a plane if and only if x_3 is a lawyer we can infer that for all x_3, if x_3 were a lawyer, then x_3 is taking a plane. From the fact that for all x_3, if x_3 were sad, then x_3 is a lawyer, and that for all x_3, if x_3 were a lawyer, then x_3 is taking a plane we can infer that for all x_3, if x_3 were sad, then x_3 is taking a plane. Finally, from the fact that for all x_3, if x_3 were sad, then x_3 is taking a plane, that for all x_3, if x_3 climbs a mountain, then x_3 is taking a plane, and that there is at least one x_3 for which x_3 is sad or x_3 will climb a mountain we can infer that there is at least one x_3 for which x_3 will take a plane. Therefore, the answer is yes.