Consider the following premises. John is not a janitor. It is not snowing. If Joseph were a soldier, then John is a janitor. It is snowing if and only if David is curious. Can we infer the following from them? David is not curious.
 From the fact that if Joseph were a soldier, then John is a janitor, and that John is not a janitor we can infer that Joseph is not a soldier. Finally, from the fact that it is snowing if and only if David is curious, and that it is not snowing we can infer that David is not curious. Therefore, the answer is yes.