Consider the following premises. For all y, y will not take a plane. There is at least one y for which y will read a book if and only if y will take a plane. Can we infer the following from them? If we can, name the inference rule being used: There is at least one y for which y will not read a book.
 From the fact that there is at least one y for which y will read a book if and only if y will take a plane we can infer that there is at least one y for which if y reads a book, then y is taking a plane via existential biconditional elimination. Finally, from the fact that there is at least one y for which if y reads a book, then y is taking a plane, and that for all y, y will not take a plane we can infer that there is at least one y for which y will not read a book via existential modus tollens. Therefore, the answer is yes.