痛定思痛 ---------- draw a lesson from a bitter experience
例句： A: I am disappointed in a love affair. Rose likes someone else.
我失恋了，罗丝爱上了别人。 B: Yon need draw a lesson from a bitter experience.
你需要痛定思痛。 微不足道 -------- not worth mentioning
例句： A: I don't know how to thank you. I am really very grateftal to you for stopping to help me.
真不知道该怎么感谢你。谢谢你停下来帮我。 B: Oh, that's all right. It is not worth mentioning actually.
啊，没什么。真的微不足道。
同义词：
insignificant
negligible trifling
be knee-high to a grasshopper
