Consider the following premises. q_2 -> t. ~q_2. t -> s. q_2 or ~s. Can we infer s from them?
 From q_2 -> t, t -> s we can infer q_2 -> s. From q_2 or ~s we can infer s -> q_2. From q_2 -> s, s -> q_2 we can infer q_2 <-> s. Finally, from q_2 <-> s, ~q_2 we can infer ~s, which contradicts s. Therefore, the answer is no.