Consider the following premises. For all y, y will not play tennis. For all y, y will drink water or y is excited. There is at least one y for which y will sleep. For all y, y will play tennis if and only if y will drink water. Can we infer the following from them? There is at least one y for which y is excited and y will sleep.
 From the fact that for all y, y will play tennis if and only if y will drink water, and that for all y, y will not play tennis we can infer that for all y, y will not drink water. From the fact that for all y, y will drink water or y is excited, and that for all y, y will not drink water we can infer that for all y, y is excited. Finally, from the fact that for all y, y is excited, and that there is at least one y for which y will sleep we can infer that there is at least one y for which y is excited and y will sleep. Therefore, the answer is yes.