Consider the following premises. If David were a lawyer, then it is overcast. If John takes a plane, then David is a lawyer. John is taking a plane and Richard is fast. Can we infer the following from them? It is overcast.
 From the fact that John is taking a plane and Richard is fast we can infer that John is taking a plane. From the fact that if John takes a plane, then David is a lawyer, and that if David were a lawyer, then it is overcast we can infer that if John takes a plane, then it is overcast. Finally, from the fact that if John takes a plane, then it is overcast, and that John is taking a plane we can infer that it is overcast. Therefore, the answer is yes.