英语听力文摘 你是福尔摩斯吗？
I was reading this mystery novel last night, and in it this guy goes missing and then a week later they find his body floating in a nearby lake. I don’t get it–I have a hard enough time staying a float for ten minutes, and I’m alive. It’s a mystery how corpses do it.
Let’s see if we can figure this mystery out. The first clue is that the density 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.
You’d think a corpse would sink as the air in its lungs is replaced by water. And they do–at least initially. But when any organism dies, it goes through putrefaction, the series of chemical, physical, and biological changes that end up returning the body to the food chain.
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 gases including carbon dioxide, ammonia, hydrogen, and methane.
I give up! What does that have to do with floating?
Well, these gasses accumulate in the body’s cavities, and–if it’s submerged in water–eventually cause it to start rising.
Gross!
Decomposition happens more slowly in water, and even more slowly in cold water.
So the mystery solved!
昨晚，我读了一本侦探小说，里面有个家伙失踪了。一周后大家在附近的河面发现他的尸首。我不太明白。我一个大活人，要浮在水面十分钟尚且不易，一具尸体为什么会浮起来呢?
我们来试着解读奥秘吧!第一个线索是：人的身体密度近似于水的。人能浮于水面的关键在于肺部的空气而不是靠在水中扑腾。
你可能认为，死者充满空气的肺部呛入水后就会尸沉水下。确实如此，至少刚开始是这样。任何生物体死后都难逃腐烂。腐烂需要经历化学反应、物理变化和生理变化，最终的躯壳再回归到食物链。
生物体死后，通常存在于消化系统的细菌继续靠机体软组织里的蛋白质和糖分为生并释放二氧化碳、氨气、氢气和甲烷等气体。
我不猜了!这些和尸首浮于水面有什么联系呢?
尸沉水下，这些气体将汇集在体腔里，最终尸浮水面。
真恶心!
在水里的尸体相对腐烂更慢，尤其是在低温水域。
谜底揭开啦!
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