Consider the following premises. For all z, z will climb a mountain if and only if z will read a book. For all z, if z were fast, then z is climbing a mountain. For all z, if z climbs a mountain, then z is fast. There is at least one z for which z will not read a book. Can we infer the following from them? There is at least one z for which z is not fast.
 From the fact that for all z, if z were fast, then z is climbing a mountain, and that for all z, if z climbs a mountain, then z is fast we can infer that for all z, z is fast if and only if z will climb a mountain. From the fact that for all z, z will climb a mountain if and only if z will read a book, and that there is at least one z for which z will not read a book we can infer that there is at least one z for which z will not climb a mountain. Finally, from the fact that for all z, z is fast if and only if z will climb a mountain, and that there is at least one z for which z will not climb a mountain we can infer that there is at least one z for which z is not fast. Therefore, the answer is yes.