Consider the following premises. forall z: U(z) -> ~W(z). forall z: W(z). U(a_5) or t. Can we infer t from them? If possible, name the inference rules being used at each step.
 From forall z: U(z) -> ~W(z), forall z: W(z) we can infer forall z: ~U(z) via universal modus tollens. From forall z: ~U(z) we can infer ~U(a_5) via universal instantiation. Finally, from U(a_5) or t, ~U(a_5) we can infer t via disjunctive syllogism. Therefore, the answer is yes.