F-8：fish in troubled waters 浑水摸鱼
A:Do you know Jim?
A:你了解吉姆吗？
B:Yes. We were classmates three years ago.
B：是的，我们曾同学三年。
A:What do you think of him?
A：你觉得他这人怎么样？
B:He has always been good at fishing in troubled waters.
B：他总爱乘人之危。
