Consider the following premises. There is at least one x_6 for which x_6 will read a book or x_6 is a taxi driver. For all x_6, if x_6 were a taxi driver, then x_6 is sad. For all x_6, x_6 will not read a book or x_6 is excited. For all x_6, x_6 is excited if and only if x_6 is sad. Can we infer the following from them? For all x_6, x_6 is not sad.
 From the fact that there is at least one x_6 for which x_6 will read a book or x_6 is a taxi driver, and that for all x_6, x_6 will not read a book or x_6 is excited we can infer that there is at least one x_6 for which x_6 is a taxi driver or x_6 is excited. From the fact that for all x_6, x_6 is excited if and only if x_6 is sad we can infer that for all x_6, if x_6 were excited, then x_6 is sad. Finally, from the fact that for all x_6, if x_6 were a taxi driver, then x_6 is sad, that for all x_6, if x_6 were excited, then x_6 is sad, and that there is at least one x_6 for which x_6 is a taxi driver or x_6 is excited we can infer that there is at least one x_6 for which x_6 is sad, which contradicts that For all x_6, x_6 is not sad. Therefore, the answer is no.