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来源:雅诚德英语网
Prices fluctuate, in response to harvests, natural disasters and political instability; and when they rise, it takes some time before new sources of supply become available.
价格会随着收成、自然灾害和政治不稳定而波动;当价格上涨时,需要一段时间才能找到新的供应来源。