他们关于哲学的对话出奇地深刻且发人深省。

Their conversation about philosophy was surprisingly ___deep and thought-provoking.

我们可以从古代的深刻思想家中获得宝贵的见解。

We can gain valuable insights from the ___deep thinkers of ancient times.

他对小说主题的分析太深刻，休闲读者难以完全欣赏。

His analysis of the novel's themes is too ___deep for casual readers to fully appreciate.