【英语时差8，16】为什么尸体会浮
时间：2015-10-19 06:10:33
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（单词翻译）
Don: Ya?l, I was reading this mystery novel last night, and in it this guy goes missing and then--lo and behold--a week later they find his body floating in a nearby lake. I don't get it--I have a hard enough time staying afloat for ten minutes, and I'm alive. It's a mystery how corpses2 do it.
Ya?l: Well, let's see if we can figure this mystery out. The first clue is that the
density3 of the human body is similar to the density of water, and what keeps us floating--other than the dog paddle--is the air in our lungs.
D: Okay, so you'd think a
corpse1 would sink as the air in its lungs is replaced by water.
Y: Well, they do--at least
initially4. But when any organism dies, it goes through putrefication, the series of chemical, physical, and biological changes that end up returning the body to the food chain. That's your second clue.
D: Hmm! I still don't get it.
Y: Okay, so here's your third clue: when a body dies, the bacteria that normally live in the digestive system continue to feed on the proteins and sugar in the body's soft tissues, and to excrete gasses including carbon dioxide, ammonia, hydrogen, and
methane5.
D: I give up. What does that have to do with floating?
Y: Well, these gasses accumulate in the body's cavities, and--if it's submerged in water--eventually cause it to start rising.
D: Gross. So why do the
villains6 always drown their victims?
Y: Well,
decomposition7 happens more slowly in water, and even more slowly in cold water.
D: So the mystery's solved.
Y: Took you long enough!
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