ponder ·verb
Definition: to think carefully about something Level: C2
他思考了如果他没回家可能会发生什么。
He ___pondered what might have happened if he hadn't gone home.
然而，我仍在思考，并且仍然不确定它的含义，所以我问自己，爬山对我来说会是一个挑战吗？
However, I am still ___pondering and I am still not quite sure of what it means and so I asked myself, would climbing a mountain be a challenge for me?
这位哲学家深入思考了存在的本质。
The philosopher ___pondered the nature of existence deeply.