Speculators do play an important role in setting the price of oil and other raw materials.But they do so based on their expectations of future trends in supply and demand, not on whims.

• 投机者的确在原油和其它原材料的定价上起着重要的作用，但是他们能实现这一点是基于他们对未来供求关系的预期，并不是头脑发热的奇思怪想。