Consider the following premises. It is raining. Elisabeth is writing a letter if and only if it is raining. Mary is a lawyer. Can we infer the following from them? If we can, name the inference rule being used: Elisabeth is writing a letter and Mary is a lawyer.
 From the fact that Elisabeth is writing a letter if and only if it is raining we can infer that if it rains, then Elisabeth is writing a letter via biconditional elimination. From the fact that if it rains, then Elisabeth is writing a letter, and that it is raining we can infer that Elisabeth is writing a letter via modus ponens. Finally, from the fact that Elisabeth is writing a letter, and that Mary is a lawyer we can infer that Elisabeth is writing a letter and Mary is a lawyer via conjunction. Therefore, the answer is yes.