Miles is sitting on the ridge of the roof , his knees splayed on the shingles , like a human clothespin , staring at a speck on the southern horizon .
麦尔斯正坐在屋脊上，膝盖斜靠在屋顶板上，就像一个人形衣夹，他正盯着南方天际中的某一点出神。
When infants 18 months old see an unrelated adult whose hands are full and who needs assistance opening a door or picking up a dropped clothespin , they will immediately help , michael tomasello writes in " why we cooperate , " a book published in october .
