Consider the following premises. Karen is not a server. Robert is writing a letter. If Sarah works, then Jennifer is not a doctor. Karen is a server or Jennifer is a doctor. Can we infer the following from them? If we can, name the inference rule being used: Sarah is working.
 From the fact that Karen is a server or Jennifer is a doctor, and that Karen is not a server we can infer that Jennifer is a doctor via disjunctive syllogism. Finally, from the fact that if Sarah works, then Jennifer is not a doctor, and that Jennifer is a doctor we can infer that Sarah is not working via modus tollens, which contradicts that Sarah is working. Therefore, the answer is no.