Consider the following premises. For all x_8, x_8 is a mechanic if and only if x_8 is a nurse. For all x_8, x_8 is a nurse and x_8 will work. Can we infer the following from them? There is at least one x_8 for which x_8 is not a mechanic.
 From the fact that for all x_8, x_8 is a mechanic if and only if x_8 is a nurse we can infer that for all x_8, if x_8 were a nurse, then x_8 is a mechanic. From the fact that for all x_8, x_8 is a nurse and x_8 will work we can infer that for all x_8, x_8 is a nurse. Finally, from the fact that for all x_8, if x_8 were a nurse, then x_8 is a mechanic, and that for all x_8, x_8 is a nurse we can infer that for all x_8, x_8 is a mechanic, which contradicts that There is at least one x_8 for which x_8 is not a mechanic. Therefore, the answer is no.