Consider the following premises. For all x_9, x_9 will play tennis. For all x_9, if x_9 were fast, then x_9 is drinking water. For all x_9, if x_9 were a taxi driver, then x_9 is drinking water. There is at least one x_9 for which x_9 is fast or x_9 is a taxi driver. Can we infer the following from them? If we can, name the inference rule being used: For all x_9, either x_9 will play tennis or x_9 will drink water are not true.
 From the fact that for all x_9, if x_9 were fast, then x_9 is drinking water, that for all x_9, if x_9 were a taxi driver, then x_9 is drinking water, and that there is at least one x_9 for which x_9 is fast or x_9 is a taxi driver we can infer that there is at least one x_9 for which x_9 will drink water via existential disjunction elimination. Finally, from the fact that for all x_9, x_9 will play tennis, and that there is at least one x_9 for which x_9 will drink water we can infer that there is at least one x_9 for which x_9 will play tennis and x_9 will drink water via existential conjunction, which contradicts that For all x_9, either x_9 will play tennis or x_9 will drink water are not true. Therefore, the answer is no.