Consider the following premises. For all x_9, if x_9 were happy, then x_9 is reading a book. For all x_9, if x_9 sleeps, then x_9 is reading a book. For all x_9, x_9 will write a letter. For all x_9, x_9 is happy or x_9 will sleep. For all x_9, if x_9 reads a book, then x_9 is drinking water. Can we infer the following from them? There is at least one x_9 for which x_9 will not write a letter.
 From the fact that for all x_9, if x_9 were happy, then x_9 is reading a book, that for all x_9, if x_9 sleeps, then x_9 is reading a book, and that for all x_9, x_9 is happy or x_9 will sleep we can infer that for all x_9, x_9 will read a book. From the fact that for all x_9, if x_9 reads a book, then x_9 is drinking water, and that for all x_9, x_9 will read a book we can infer that for all x_9, x_9 will drink water. From the fact that for all x_9, x_9 will drink water, and that for all x_9, x_9 will write a letter we can infer that for all x_9, x_9 will drink water and x_9 will write a letter. Finally, from the fact that for all x_9, x_9 will drink water and x_9 will write a letter we can infer that for all x_9, x_9 will drink water, which contradicts that There is at least one x_9 for which x_9 will not write a letter. Therefore, the answer is no.