Consider the following premises. For all x, if x were a carpenter, then x is writing a letter. For all x, if x writes a letter, then x is taking a plane. For all x, if x takes a plane, then x is curious. For all x, if x were curious, then x is a carpenter. Can we infer the following from them? For all x, if x writes a letter, then x is a carpenter.
 From the fact that for all x, if x takes a plane, then x is curious, and that for all x, if x were curious, then x is a carpenter we can infer that for all x, if x takes a plane, then x is a carpenter. Finally, from the fact that for all x, if x writes a letter, then x is taking a plane, and that for all x, if x takes a plane, then x is a carpenter we can infer that for all x, if x writes a letter, then x is a carpenter. Therefore, the answer is yes.