1.someone who is very strict or very determined
1.So I think Iran is always going to be a tough nut to crack , but I think it is worth a try .
因此我认为，伊朗和以前一样，还是一颗硬钉子，不过值得去努力。
2.Michael Jackson appears to be a tough nut to break.
迈克尔·杰克逊似乎是一个颇为棘手的问题。
3.It was however an important contrast to Scolari's only home encounter with Hull City who again proved a tough nut to crack.
无疑，这场比赛是和斯科拉里主场遭遇赫尔城一战的重要对比，赫尔城再一次证明了自己是根难啃的骨头。
4.What makes the brain such a tough nut to crack?
大脑何以成为一座难以攻克的堡垒？
5.It strikes me that he's right a tough nut to crack.
在我看来，他可是个难对付的家伙。
6.Of course, cracking new chip markets isn't easy, and the cell phone business may prove an especially tough nut for Intel.
开发新的芯片市场当然不是件容易的事，手机业务尤其困难，可能会成为英特尔面前的一块硬骨头。
7.I also agree that figuring out how to reduce the power of wealth over policy and politics is a tough nut to crack.
我同样认为分析清如何减少财富的权力对政策和政治的影响亦非易事。
8.There are some promising drugs in the pipeline. But it's been a really tough nut to crack.
有一些前景不错的药品已经在研发之中，但要真正实现确实还很不容易。
9.eg: It is a tough nut for him to crack.
这对他而言是一个难题。
10.Don't annoy him. He's a real tough nut.
别惹他，他可是个难对付的家伙。