冥思苦想

I puzzled over the problem for ages before the light suddenly dawned on me.

我对这个问苦想了很久才豁然开朗。

As people grow older, they begin to ruminate on the uncertainty of life.

随着年龄的增长，人们开始对活的变化无常苦想。

He puzzled his brains to find an answer.

他苦想寻求答案。