Consider the following premises. If William were a lawyer, then Robert is reading a book. If William were not a lawyer, then Thomas is writing a letter. Robert is not reading a book. Can we infer the following from them? Thomas is writing a letter or it is cloudy.
 From the fact that if William were a lawyer, then Robert is reading a book, and that Robert is not reading a book we can infer that William is not a lawyer. From the fact that if William were not a lawyer, then Thomas is writing a letter, and that William is not a lawyer we can infer that Thomas is writing a letter. Finally, from the fact that Thomas is writing a letter we can infer that Thomas is writing a letter or it is cloudy. Therefore, the answer is yes.