Before six-month-olds, Piaget observed, you take an object the kid likes like a rattle, you hide it, you put it behind something, it's like it's gone.

皮亚杰发现,在六个月之前,你将婴儿喜欢的物体,比如说拨浪鼓,藏起来,隐藏在某物的后面,就像这东西消失了一样

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