他多年来一直受到膝盖旧伤的困扰。

He has been dealing with a ___troublesome knee injury for years.

在国外工作可能会让你遇到棘手的状况，但有经验的工人知道如何处理。

Working abroad can expose you to ___troublesome situations, but experienced workers know how to handle them.

气候变化这一棘手问题需要长期解决方案。

The ___troublesome issue of climate change requires long-term solutions.