Studies have been done in the city of New York where you can-- if you live in Manhattan you can actually get a very nice metric of how far apart people live from each other in city blocks. Right?

纽约市就做过这类实验,在纽约-,如果你生活在曼哈顿,你能准确地测量,生活不同街道的人相互距离多远？

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