我们进行了一次关于人生的深刻而有意义的对话。

We had a ___deep and meaningful conversation about life.

我认为我们真的需要回归经典，从深刻的思想家那里汲取一些东西。

I think we really need to go back to the classics to receive something from the ___deep thinkers.

他的哲学著作很深刻，需要仔细研究。

His philosophical writings are ___deep and require careful study.