Consider the following premises. Barbara is drinking water or it is not late. If Barbara drinks water, then it is late. It is late. Can we infer the following from them? Barbara is drinking water.
 From the fact that Barbara is drinking water or it is not late we can infer that if it is late, then Barbara is drinking water. From the fact that if it is late, then Barbara is drinking water, and that if Barbara drinks water, then it is late we can infer that it is late if and only if Barbara is drinking water. From the fact that it is late if and only if Barbara is drinking water we can infer that if it is late, then Barbara is drinking water. Finally, from the fact that if it is late, then Barbara is drinking water, and that it is late we can infer that Barbara is drinking water. Therefore, the answer is yes.