He would try to explain it this way when students asked for a top grade just for studying hard in chemistry class: What if a baseball player came to spring training and worked harder than all the others, but still could not play well.

VOA: special.2009.03.12

It's hard to explain exactly what it is, It's not getting lost.

很难解释它到底是什么，不是迷途。

普林斯顿公开课 - 人性课程节选

It's hard to explain. I'm not an expert, so I just...

这很难解释。我不是一个专家，所以我只能……

英国的啤酒 - SpeakingMax英语口语达人

Altruism" is the biologists' term meaning kindness,generosity, and evolutionary biologists have worked really hard to explain why animals might evolve to be kind.

利他主义是生物学术语,意思是善良，慷慨，进化生物学家努力去解释,为什么动物进化趋向善良。

耶鲁公开课 - 心理学导论课程节选

It's very hard to see how you explain that in physicalist terms.

都很难运用物理主义术语加以解释

耶鲁公开课 - 死亡课程节选