open up a can of worms 捅马蜂窝 (适用于problem类型题)

如：I think the government opened up a can of worms when they decided to ban smoking in public places. 当政府规定禁止在公共场合吸烟时，我认为他们捅了马蜂窝。

或者这个动词open不用也行：

Banning smoking in public places turned out to be a real can of worms for the government. 事实证明，对政府而言，禁止在公共场所吸烟的规定是真正的“捅马蜂窝”。

let sleeping dogs lie 莫惹是非 （适用于solution类型题）

There's no point in making new traffic laws. I think we should just let sleeping dogs lie. 制定新的交通法毫无意义。我想我们只要不惹是生非就好。

sth. should come back to bite you 某事可能会回来找你麻烦 (适用于disadvantage题型)

Are there any disadvantages of exercising?

I suppose there are always some drawbacks.A potential negative result is that too much exercise could come back to bite you! For instance, in the future you could develop arthritis /ɑː'θraɪtɪs/ or muscle injuries /'ɪn(d)ʒ(ə)rɪ/ ! 我觉得有很多不利的点。一个潜在的负面结果是过多的锻炼可能会给你带来麻烦。如，将来你可能患上关节炎和肌肉伤痛等症状。