Consider the following premises. If Robert drinks water, then Robert is excited. For all y, if y were excited, then y is a cashier. Mary is not cooking. For all y, if y were a cashier, then y is drinking water. Mary is cooking if and only if Robert is excited. Can we infer the following from them? Robert is drinking water.
 From the fact that for all y, if y were excited, then y is a cashier, and that for all y, if y were a cashier, then y is drinking water we can infer that for all y, if y were excited, then y is drinking water. From the fact that for all y, if y were excited, then y is drinking water we can infer that if Robert were excited, then Robert is drinking water. From the fact that if Robert drinks water, then Robert is excited, and that if Robert were excited, then Robert is drinking water we can infer that Robert is drinking water if and only if Robert is excited. From the fact that Mary is cooking if and only if Robert is excited, and that Mary is not cooking we can infer that Robert is not excited. Finally, from the fact that Robert is drinking water if and only if Robert is excited, and that Robert is not excited we can infer that Robert is not drinking water, which contradicts that Robert is drinking water. Therefore, the answer is no.