And the problem is, that we want to build this abstract data type, but we'd like to basically know what kind of object is it, and what functions actually belong to it, how do we use them?

然后我对它们运行了这个方法，就是这一小段代码这个方法,这有意义么？,当然没有了，对不对？,因为你知道，当你把两个极坐标，表示的点进行相加运算的时候？

麻省理工公开课 - 计算机科学及编程导论课程节选

It's an interesting question as to whether he really explains how a child goes from a concrete thinker to an abstract thinker, or how he goes from not having object permanence to understanding object permanence.

问题是,他是否真的解释了,儿童思维是如何从具体向抽象转变的,或是真的解释了,儿童的客体永存性概念是如何从无到有的

耶鲁公开课 - 心理学导论课程节选