Now, that's actually a difficult question to ask-- to answer for a child, but I tried my best to give him an answer.

向一个孩子解释这个问题其实挺困难的，但我还是尽力给了他一个答案。

耶鲁公开课 - 心理学导论课程节选

I mean, I've looked through everything; I can't find any earlier reference.

我尽力查阅所有相关文献,但我找不到更早的了

耶鲁公开课 - 金融市场课程节选