Consider the following premises. There is at least one x_12 for which if x_12 writes a letter, then x_12 is an office clerk. For all x_12, if x_12 works, then x_12 is an office clerk. For all x_12, if x_12 were an office clerk, then x_12 is writing a letter. For all x_12, if x_12 were an office clerk, then x_12 is working. Can we infer the following from them? If we can, name the inference rule being used: For all x_12, the fact that x_12 works does not imply that x_12 is writing a letter.
That contradicts the premises. Therefore the answer is no.