a bad apple的用法和样例：
- There's always a bad apple in every bunch.
- I looked her up and down unconcernedly, say: "Picture, it is a bad apple nevertheless.
- The corruption in the government started with a bad apple, a high official two years ago. Now the whole system is corrupt.
- Oh, my God! What happened? Why are you black and blue? B: I got beaten by Peter's brotherA: That's a bad apple! Let's think up a way and teach him a lesson.
- There's one bad apple for every three good ones.
a bad apple的相关资料：