Definition: serious and difficult to understand Level: C2
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.
