At first it might be counter-intuitive because we know the probability density at the nucleus is the greatest.

起初我们觉得这和直观感觉很不相符,因为我们知道在原子核,出的概率密度是最高的。

麻省理工公开课 - 化学原理课程节选

So, he's using intuitive-- he says difficult or easy-- so he says it's difficult, meaning the probability is very low, or easy, meaning that probability is high.

所以他直接进行了描述,他用的是困难和简单两词,他说的困难,意思就是概率很小,他说的简单,意思就是概率很大

耶鲁公开课 - 金融市场课程节选