And how we figure that out and how we move in a direction that's both effective and affordable is the work that has to be done over the next two years."

VOA: standard.2010.03.26

If you want to write it as a vector equation, you want to write it as v square over r minus-- I want to say that it's pointing in the direction toward the center.

如果要写出矢量方程,就应该写成 -v^2 / r,也就是说,方向就向圆心

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