Consider the following premises. For all x_11, if x_11 plays squash, then x_11 is a taxi driver. For all x_11, x_11 will take a plane if and only if x_11 is an electrician. For all x_11, if x_11 drinks water, then x_11 is playing squash. For all x_11, if x_11 were a taxi driver, then x_11 is an electrician. For all x_11, x_11 will not take a plane. Can we infer the following from them? If we can, name the inference rule being used: For all x_11, x_11 will not drink water.
 From the fact that for all x_11, x_11 will take a plane if and only if x_11 is an electrician, and that for all x_11, x_11 will not take a plane we can infer that for all x_11, x_11 is not an electrician via universal biconditional elimination. From the fact that for all x_11, if x_11 were a taxi driver, then x_11 is an electrician, and that for all x_11, x_11 is not an electrician we can infer that for all x_11, x_11 is not a taxi driver via universal modus tollens. From the fact that for all x_11, if x_11 plays squash, then x_11 is a taxi driver, and that for all x_11, x_11 is not a taxi driver we can infer that for all x_11, x_11 will not play squash via universal modus tollens. Finally, from the fact that for all x_11, if x_11 drinks water, then x_11 is playing squash, and that for all x_11, x_11 will not play squash we can infer that for all x_11, x_11 will not drink water via universal modus tollens. Therefore, the answer is yes.