a woman lives on the tenth floor of an apartment building. every morning she takes the elevator all the way down, and goes to work. in the evening, she gets into the elevator, and goes to work. in the evening, she gets into the elevator, and if there is someone else in it she goes back to her floor directly. otherwise, she goes to the seventh floor and walks up three flights of stairs to her apartment. why?
she's too short to reach the buttons, or she likes exercise