His to-do list was dispiritingly inadequate on some of the thorniest problems.

在一些最棘手的问题上，他的待办事项清单令人沮丧地不足。

This is one of the biggest and thorniest questions.

这是现在最大也是最棘手的几个问题之一。

Paradoxically, the thorniest outstanding issue involves Bolivia.

而荒谬可笑的是，最棘手的国家要事却牵涉到了玻利维亚。

Testing performance is one of the thorniest areas of unit testing.

测试性能是单元测试最为痛苦的方面之一。

This has become one of the thorniest issues in the REDD negotiations.

这成为在REDD谈判中的最棘手的问题之一。