Consider the following premises. There is at least one x for which x is a janitor if and only if x is a nurse. For all x, if x were a taxi driver, then x is a nurse. Can we infer the following from them? If we can, name the inference rule being used: For all x, the fact that x were a taxi driver does not imply that x is a janitor.
That contradicts the premises. Therefore the answer is no.