Consider the following premises. For all z, z is a carpenter if and only if z will take a plane. Charles is a carpenter or it is cloudy. It is cloudy if and only if Charles is taking a plane. Can we infer the following from them? Charles is taking a plane.
 From the fact that for all z, z is a carpenter if and only if z will take a plane we can infer that Charles is a carpenter if and only if Charles is taking a plane. From the fact that Charles is a carpenter if and only if Charles is taking a plane we can infer that if Charles were a carpenter, then Charles is taking a plane. From the fact that it is cloudy if and only if Charles is taking a plane we can infer that if it is cloudy, then Charles is taking a plane. Finally, from the fact that if Charles were a carpenter, then Charles is taking a plane, that if it is cloudy, then Charles is taking a plane, and that Charles is a carpenter or it is cloudy we can infer that Charles is taking a plane. Therefore, the answer is yes.