来自《耶鲁大学开放课程：基础物理 第3集 第3集》

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  I mentioned something of increasing importance only later,
  后来我又讲了更重要的知识点
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  which is that you are free to pick another set of axes,
  你可以随意选取另外一个坐标系
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  not in the traditional x and y direction,
  不再是传统的 x 和 y 方向
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  but as an oblique direction.
  而是倾斜过的方向
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  If you do,
  如果这么做
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  the unit vectors are called i prime and j prime,
  单位矢量就是 i' 和 j'
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  the components of the vector change.
  矢量的两个分量也会发生变化
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  You can imagine that if a vector is viewed from an angle,
  你可以想象一下 如果换一个角度观察矢量
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  then its components will vary with the perspective.
  其分量会相应地发生变化
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  So the components of the vector
  矢量的两个分量
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  are not invariant characterizations of the vector.
  并不是一成不变的
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  That is, the vector itself has a life of its own.
  也就是说 矢量本身是独立的