Consider the following premises. Elisabeth is not playing squash. For all x_7, x_7 will play squash if and only if x_7 is an electrician. Can we infer the following from them? If we can, name the inference rule being used: Elisabeth is an electrician.
 From the fact that for all x_7, x_7 will play squash if and only if x_7 is an electrician we can infer that Elisabeth is playing squash if and only if Elisabeth is an electrician via universal instantiation. From the fact that Elisabeth is playing squash if and only if Elisabeth is an electrician we can infer that if Elisabeth were an electrician, then Elisabeth is playing squash via biconditional elimination. Finally, from the fact that if Elisabeth were an electrician, then Elisabeth is playing squash, and that Elisabeth is not playing squash we can infer that Elisabeth is not an electrician via modus tollens, which contradicts that Elisabeth is an electrician. Therefore, the answer is no.