Hobrooke admits is a very complicated and difficult problem to address.

VOA: standard.2009.06.15

Now, as I said last time, the subject of free will--or free will, determinism, causation and responsibility, this cluster of problems-- is an extremely difficult and complicated physical problem.

正如我上次所说的,自由意志这个主题 或者说自由意志,决定论,因果论,责任,这一堆问题,是极端困难和复杂的物理问题

耶鲁公开课 - 死亡课程节选

That's a complicated thing that accountants figure out and accountants find it difficult to define the earnings of a company, but they do something and they come up with a number.

会计们会计算这个复杂的问题,他们还会发现公司收益很难定义,但是他们会想办法,得出一个数字

耶鲁公开课 - 金融市场课程节选