Consider the following premises. For all x_7, x_7 will not play squash. There is at least one x_7 for which x_7 is happy. For all x_7, x_7 will play squash. Can we infer the following from them? There is at least one x_7 for which x_7 will take a plane.
 From the fact that for all x_7, x_7 will play squash we can infer that for all x_7, x_7 will play squash or x_7 will take a plane. From the fact that for all x_7, x_7 will play squash or x_7 will take a plane, and that for all x_7, x_7 will not play squash we can infer that for all x_7, x_7 will take a plane. From the fact that for all x_7, x_7 will take a plane, and that there is at least one x_7 for which x_7 is happy we can infer that there is at least one x_7 for which x_7 will take a plane and x_7 is happy. Finally, from the fact that there is at least one x_7 for which x_7 will take a plane and x_7 is happy we can infer that there is at least one x_7 for which x_7 will take a plane. Therefore, the answer is yes. Notice, however, that the premises were contradictory, so we can infer anything from them.