Consider the following premises. forall x: ~R(x). p_2 or R(a_17). ~p_2 or t. Can we infer ~t from them?
 From forall x: ~R(x) we can infer ~R(a_17). From p_2 or R(a_17), ~p_2 or t we can infer R(a_17) or t. Finally, from R(a_17) or t, ~R(a_17) we can infer t, which contradicts ~t. Therefore, the answer is no.