来自《耶鲁大学开放课程：基础物理 第3集 第3集》

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  That's what I'm going to emphasize,
  所以我一直强调
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  more than just plugging in the numbers.
  它不仅仅是代数字这么简单
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  Of course, we have to also know how to plug in the numbers
  当然 我们首先要知道怎么代数字
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  so we can pass all the tests,
  这样我们考试才能过关
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  but it's good to understand
  但是如果能理解
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  the nature of the edifice set up by Newton.
  牛顿的这一伟大杰作的本质就更好了
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  First statement by Newton-- I don't feel like writing it down.
  牛顿第一定律 我不想写出来
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  It's too long and everybody knows what the law is.
  太长了 而且大家应该都知道
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  It's called the Law of Inertia.
  又名惯性定律
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  Let me just say it and talk about it.
  我先复述一遍再来讨论
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  The Law of Inertia says that,
  惯性定律就是
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  "If a body has no forces acting on it,
  "如果一个物体不受外力作用