Consider the following premises. For all x_8, x_8 will drink water or x_8 will work. David is drinking water if and only if James is sleeping. James is not sleeping. Can we infer the following from them? If we can, name the inference rule being used: David is not working.
 From the fact that for all x_8, x_8 will drink water or x_8 will work we can infer that David is drinking water or David is working via universal instantiation. From the fact that David is drinking water if and only if James is sleeping, and that James is not sleeping we can infer that David is not drinking water via biconditional elimination. Finally, from the fact that David is drinking water or David is working, and that David is not drinking water we can infer that David is working via disjunctive syllogism, which contradicts that David is not working. Therefore, the answer is no.