来自《耶鲁大学开放课程：资本主义：成功、危机与改革 第3集 第3集》

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  but most of the people would pass the polygraph test
  但相信他的人就算用测谎也没用
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  that they believe it's there.
  他们还会相信这个理论还存在
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  Okay, that's good.
  很好
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  Now let's--here's an interesting exercise.
  这有个有趣的例子
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  There are about a dozen MBAs in the group here.
  这个组里有部分工商管理硕士
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  Every MBA--every MBA period, has learned the Porter Forces.
  每位工商管理硕士都学过波特五力模型
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  What are the Porter Forces?
  什么是波特五力模型呢
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  The Porter Forces are the rules of thumb you need to make
  波特五力模型是企业获得
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  above average profits within a firm.
  高于行业平均利润的经验原则
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  One of them is: You don't want too much competition--direct competition.
  其中一条是要避免过多的直接竞争
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  Direct competition erodes profits.
  直接竞争会损害利润
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  You want high barriers to entry.
  你想给市场设立高门槛