Consider the following premises. If Elisabeth were an office clerk, then Jessica is playing squash. Elisabeth is drinking water if and only if Jessica is playing squash. Elisabeth is an office clerk if and only if Elisabeth is drinking water. Can we infer the following from them? If we can, name the inference rule being used: The fact that Elisabeth were an office clerk does not imply that Elisabeth is drinking water.
 From the fact that Elisabeth is drinking water if and only if Jessica is playing squash we can infer that if Jessica plays squash, then Elisabeth is drinking water via biconditional elimination. Finally, from the fact that if Elisabeth were an office clerk, then Jessica is playing squash, and that if Jessica plays squash, then Elisabeth is drinking water we can infer that if Elisabeth were an office clerk, then Elisabeth is drinking water via transitivity, which contradicts that The fact that Elisabeth were an office clerk does not imply that Elisabeth is drinking water. Therefore, the answer is no.