来自《耶鲁大学开放课程：新生有机化学 第8集 第8集》

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  and we have to think a little bit about this,
  我们必须多想想这个
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  and we can think of it in -- by analogy, with mass density.
  我们想它在--比如以质量密度来说
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  Suppose you had a flask and
  假设你有一个瓶子
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  it had mercury and water and oil in it, right?
  装了水银 水和油在里面
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  And you're going to ask the question,
  你要问这个问题
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  if the total mask in the flask is one kilogram,
  如果瓶中的总质量为一公斤
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  what fraction of that, or how much weight,
  从底部算起一厘米的地方
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  is exactly one centimeter from the bottom?
  到底占了几分之几或者有多重
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  How many grams, or what fraction of the total do you think,
  你认为距底部一厘米的地方
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  would be exactly one centimeter from the bottom?
  有多少克或者占总体的比例有多少
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  Anybody got a guess?
  有人有猜测吗
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  12%?
  是12%吗