1、a bad apple 坏蛋
A：Oh, my God! What happened? Why are you black and blue?
B：I got beaten by Peter’s brother
A：That’s a bad apple! Let’s think up a way and teach him a lesson
甲：噢，天哪！怎么啦？你身上怎么青一块紫一块的？
乙：彼得的弟弟把我给打了。
甲：这坏蛋，咱们来想个法来教训教训他。