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