当我们碰到难题时可以说 a tough(or hard) nut to crack – 特别难打开的坚果。这个表达也能用来形容一个难以对付或难理解的人。

例句

My new boss is a tough nut to crack. I never know if he's pleased with my work.

How can we increase sales during a recession? That's a tough nut to crack!

请注意

表达 use a sledgehammer to crack a nut 用大锤来敲开一粒小坚果，实际意思是杀鸡用牛刀，小题大做。

The police sent five officers to arrest one teenage thief? That's really using a sledgehammer to crack a nut!