Consider the following premises. For all x_4, if x_4 sleeps, then x_4 is drinking water. For all x_4, if x_4 reads a book, then x_4 is drinking water. For all x_4, x_4 will read a book or x_4 will sleep. There is at least one x_4 for which x_4 will write a letter. Can we infer the following from them? There is at least one x_4 for which x_4 will write a letter and x_4 will drink water.
 From the fact that for all x_4, if x_4 reads a book, then x_4 is drinking water, that for all x_4, if x_4 sleeps, then x_4 is drinking water, and that for all x_4, x_4 will read a book or x_4 will sleep we can infer that for all x_4, x_4 will drink water. Finally, from the fact that there is at least one x_4 for which x_4 will write a letter, and that for all x_4, x_4 will drink water we can infer that there is at least one x_4 for which x_4 will write a letter and x_4 will drink water. Therefore, the answer is yes.