How does higgins respond when liza says the following? "aha! now i know how to deal with you. what a fool i was not to think of it before! you can't take away the knowledge you gave me. you said i had a finer ear than you. and i can be civil and kind to people, which is more than you can. aha! that's done you, henry higgins, it has. now i don't care that [snapping her fingers] for your bullying and your big talk. i'll advertize it in the papers that your duchess is only a flower girl