顽固的（形容词）

(adjective) Stubbornly confident in one's own opinions regardless of the advice or warnings of other; acting like a mule.

EXAMPLE: The mulish young man inherited a large fortune, but he lost all of it quickly by making disastrous business decisions everyone warned him against.

这位顽固的年轻人继承了一大笔遗产，但由于做了一些所有人都反对的商业决策，他又很快失去了全部遗产。

to plumb the depths of something

深入

To examine something very carefully in order to understand it thoroughly.

EXAMPLE: The team of young doctors plumbed the depths of medical research in order to find a cure for the mysterious disease.

为找到关于这种神秘疾病的疗法，这支由青年医生组成的团队进行了深入的医学研究。