他说，投资者将黄金看成是抵御纸币贬值的保值工具，一个由于利率较低而机会成本较小的保值工具。

He says investors see gold as a hedge against the depreciation of paper currencies, a hedge which has little opportunity cost because of low interest rates.

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老生常谈是，由于后续成本存在，普通投资者无法击败市场。研究机构由此得出观点，明显的击败市场的机会将很快会被套利耗尽。

From the truism that the average investor could not beat the market after costs, academics developed the insight that obvious market-beating opportunities would quickly be arbitraged away.

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