Say you're in the room where you're, like, practicing thumb calisthenics — which probably isn't a thing — but the room is a little chilly, so the blood feeding your dermis loses a lot of heat to that cold air.
假设你在一个房间里,在练习拇指健操——这可能不是个真事儿——但是房间有点冷,所以供给你真皮的血液在冷空气中损失了很多热量。