Oil prices seesawed last week before surging Thursday and Friday as investors bet that crude demand, which has been tepid this summer, will eventually pick up as the economy improves.

• 上周原油价格在上涨前都是高低波动着。周四周五当投资者打赌今年夏天的原油需求不温不火，最后将由于经济的提升而上涨。