translation.en: Because when you take out that last piece of gold -- and they did incredibly quickly. I mean, if you look at the 1849 Gold Rush -- the entire American river region, within two years -- every stone had been turned. And after that, only big companies who used more sophisticated mining technologies started to take gold out of there.
translation.zh: 因为，当你把最后一块黄金采掘出来的时候 这个过程是非常短暂的。我的意思是，如果你回顾1849年的淘金热—— 整个美洲地区的河流，在不到两年的时间里—— 人们翻遍了每一块石头。这样之后，只有那些大型的公司 用先进的开采技术 在那里进行黄金的开采