We've seen the price of oil, lately, move all over the map. It went up to $100 recently and it was just as late as late 1990s that it was under $20 and people just don't know where it's going to go.

我们都能看到现在石油的价格，一路飙升，最近达到每桶一百美元,而在上世纪九十年代末,每桶石油还不到二十美元0,人们根本无法预想石油价格,还会飙升到什么地步。

耶鲁公开课 - 金融市场课程节选