Consider the following premises. For all x_11, x_11 will play squash if and only if x_11 is a nurse. There is at least one x_11 for which if x_11 plays squash, then x_11 is drinking water. For all x_11, if x_11 drinks water, then x_11 is a nurse. Can we infer the following from them? There is at least one x_11 for which if x_11 drinks water, then x_11 is a nurse.
 From the fact that for all x_11, x_11 will play squash if and only if x_11 is a nurse we can infer that for all x_11, if x_11 were a nurse, then x_11 is playing squash. From the fact that for all x_11, if x_11 were a nurse, then x_11 is playing squash, and that there is at least one x_11 for which if x_11 plays squash, then x_11 is drinking water we can infer that there is at least one x_11 for which if x_11 were a nurse, then x_11 is drinking water. From the fact that for all x_11, if x_11 drinks water, then x_11 is a nurse, and that there is at least one x_11 for which if x_11 were a nurse, then x_11 is drinking water we can infer that there is at least one x_11 for which x_11 will drink water if and only if x_11 is a nurse. Finally, from the fact that there is at least one x_11 for which x_11 will drink water if and only if x_11 is a nurse we can infer that there is at least one x_11 for which if x_11 drinks water, then x_11 is a nurse. Therefore, the answer is yes.