Consider the following premises. For all y, if y makes tea, then y is an electrician. For all y, y will make tea or y is not an electrician. Can we infer the following from them? For all y, y will make tea if and only if y is an electrician.
 From the fact that for all y, y will make tea or y is not an electrician we can infer that for all y, if y were an electrician, then y is making tea. Finally, from the fact that for all y, if y makes tea, then y is an electrician, and that for all y, if y were an electrician, then y is making tea we can infer that for all y, y will make tea if and only if y is an electrician. Therefore, the answer is yes.