Consider the following premises. If Patricia works, then it is sunny. Patricia is working or it is not snowing. If Charles sleeps, then it is sunny. If it is sunny, then Charles is sleeping. Can we infer the following from them? If it snows, then Charles is sleeping.
 From the fact that if it is sunny, then Charles is sleeping, and that if Charles sleeps, then it is sunny we can infer that it is sunny if and only if Charles is sleeping. From the fact that it is sunny if and only if Charles is sleeping we can infer that if it is sunny, then Charles is sleeping. From the fact that Patricia is working or it is not snowing we can infer that if it snows, then Patricia is working. From the fact that if it snows, then Patricia is working, and that if Patricia works, then it is sunny we can infer that if it snows, then it is sunny. Finally, from the fact that if it snows, then it is sunny, and that if it is sunny, then Charles is sleeping we can infer that if it snows, then Charles is sleeping. Therefore, the answer is yes.