来自《耶鲁大学开放课程：新生有机化学 第3集 第3集》

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  it'll take the steepest way to go down.
  会发现它采取速度最快的下降路径流下
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  It turns out it crosses every contour perpendicularly.
  结果是它垂直穿过了每一条等高线
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  So you follow that
  所以你跟着它
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  and it would go down to the bottom,
  它会流到底部
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  and then if you kept going,
  如果你还继续
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  like if you dropped a marble or something,
  就像你丢下一个弹珠什么之类的
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  and it rolled down to the bottom
  它会滚到底部
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  it would keep going.
  然后继续前进
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  So there is a particularly interesting path.
  这样就会有一个特别有趣的路径
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  Not that the true molecule would necessarily have to follow that path,
  这不是说真正的分子一定会遵循这条路径
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  but it's a well-defined path
  但它是一个明确的路径
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  gets from one valley to the other.
  可从一个山谷到另一个山谷