审判时隐藏在后面的恼怒表情不见了，他长着一副好看、睿智和无害的公务员面孔。

Without the irritated expression he hid behind during the trial, he had a nice, intelligent, harmless civil servant's face.

youdao

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

耶鲁公开课 - 心理学导论课程节选