https://online1.tingclass.net/lesson/shi0529/0000/704/1_130.mp3
https://image.tingclass.net/statics/js/2012
M: The Blacks got divorced.
W: Really? Why?
M: Mr. Black has been getting a little on the side.
W: Really? I am surprised. He doesn't look like a guy who'd ever cheat on his wife, does he?
M: No, he doesn't. Anyway, his wife found out that he has been two-timing for a long time.
W: Well, I am really surprised. By the way, have you done anything behind my back?
W: No. The only thing I've ever done behind your back is zipping you up.
M: I like that joke, but I hope it's true.