Consider the following premises. For all y, y will drink water. For all y, y will sleep. For all y, if y drinks water, then y is a doctor. Can we infer the following from them? If we can, name the inference rule being used: Sarah is sleeping or it is snowing.
 From the fact that for all y, if y drinks water, then y is a doctor, and that for all y, y will drink water we can infer that for all y, y is a doctor via universal modus ponens. From the fact that for all y, y will sleep, and that for all y, y is a doctor we can infer that for all y, y will sleep and y is a doctor via universal conjunction. From the fact that for all y, y will sleep and y is a doctor we can infer that Sarah is sleeping and Sarah is a doctor via universal instantiation. From the fact that Sarah is sleeping and Sarah is a doctor we can infer that Sarah is sleeping via simplification. Finally, from the fact that Sarah is sleeping we can infer that Sarah is sleeping or it is snowing via addition. Therefore, the answer is yes.