来自《耶鲁大学开放课程：金融市场 第21集 第21集》

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  The normal course of grain prices over the harvest year
  谷物价格在种植年份的走势
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  is to rise as the year progresses.
  一般是一个上升过程
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  It has to be that way;
  这是规律
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  the grain is cheapest right after the harvest
  收割季结束时谷物是最便宜的
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  when there's lots of grain around
  因为此时供应充分
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  and then the grain price goes up steadily throughout the year
  接着谷物价格会稳步上涨
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  until the new harvest comes in and then it collapses.
  一直持续到下一季 然后又是价格猛跌
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  The price of grain over the year is a sawtooth pattern.
  每年谷物价格走势图是锯齿型的
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  If there's nothing interfering with it,
  如果没有其他干预
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  the price of grain will tend to look like this
  谷物价格看起来应该是这样
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  and these are the harvests.
  这些位置是收割季
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  The reason the price of grain is going up between harvests
  在收割季之间的谷物价格上升