【答案解析】Traders in the futures market believe that the oil price will rise again. Based on this prediction, a lot of money was invested in the building of more refineries and storage tanks. Those are what the author refers to as "bets". But these bets may not earn money for the traders and investors. The U. S. economy may slow down, as it is already doing. That would reduce demand for oil, both from America and from countries that supply it with imports. And the cheap oil price will be the best help to mitigate any slowdown.