Consider the following premises. For all z, z will work or z is not a sailor. Elisabeth is a sailor. Can we infer the following from them? If we can, name the inference rule being used: There is at least one z for which z will work.
 From the fact that for all z, z will work or z is not a sailor we can infer that for all z, if z were a sailor, then z is working via universal rewriting. From the fact that Elisabeth is a sailor we can infer that there is at least one z for which z is a sailor via existential generalization. Finally, from the fact that for all z, if z were a sailor, then z is working, and that there is at least one z for which z is a sailor we can infer that there is at least one z for which z will work via existential modus ponens. Therefore, the answer is yes.