Consider the following premises. For all y, if y drinks water, then y is an office clerk. For all y, if y works, then y is drinking water. For all y, if y were a doctor, then y is drinking water. For all y, y is a doctor or y will work. For all y, if y drinks water, then y is a doctor. Can we infer the following from them? For all y, y is an office clerk.
 From the fact that for all y, if y drinks water, then y is a doctor, and that for all y, if y were a doctor, then y is drinking water we can infer that for all y, y will drink water if and only if y is a doctor. From the fact that for all y, y will drink water if and only if y is a doctor we can infer that for all y, if y were a doctor, then y is drinking water. From the fact that for all y, if y were a doctor, then y is drinking water, that for all y, if y works, then y is drinking water, and that for all y, y is a doctor or y will work we can infer that for all y, y will drink water. Finally, from the fact that for all y, if y drinks water, then y is an office clerk, and that for all y, y will drink water we can infer that for all y, y is an office clerk. Therefore, the answer is yes.