Consider the following premises. There is at least one y for which y is a scientist. For all y, y will drink water. For all y, y is a poet if and only if y is a scientist. Can we infer the following from them? If we can, name the inference rule being used: Some poets will drink water.
 From the fact that for all y, y is a poet if and only if y is a scientist we can infer that for all y, if y were a scientist, then y is a poet via universal biconditional elimination. From the fact that for all y, if y were a scientist, then y is a poet, and that there is at least one y for which y is a scientist we can infer that there is at least one y for which y is a poet via existential modus ponens. Finally, from the fact that there is at least one y for which y is a poet, and that for all y, y will drink water we can infer that some poets will drink water via existential conjunction. Therefore, the answer is yes.