Consider the following premises. If Elisabeth were an astronaut, then William is drinking water. For all x_7, x_7 is a nurse if and only if x_7 will drink water. William is a nurse or Elisabeth is an astronaut. Can we infer the following from them? If we can, name the inference rule being used: William is a nurse or Elisabeth is an astronaut.
That is one of the premises. Therefore, the answer is yes.