【英语时差8,16】青春痘Vs毛茸脸（下）

（单词翻译）

 The big culprit on faces, though, isn’t dirt so much as an internally-produced substance called sebum that makes the skin cells shed inside the pores. These dead cells, unable to flake¹ away, collect until they become an irritation² to the pore. At this point the body reacts in a miniature version of the way it deals with any other invasion: it sends white blood cells to the site to attack the invading body. The result is a mild inflammation at the scene of battle. That inflammation is the zit. So evolution, while having cleaned our hairy faces, gave us pimply³ skin instead.