由此得出，决定井眼轨迹的是钻头合位移方向，而不必是合力方向。
The trajectory of bore hole is proved to be formed by the resultant displacement of the bit instead of the resultant force.
而这些成就的取得，绝不是由某种单一力量所决定的，而是由多种复合力量所形成的历史的合力方向所决定的。
But what these achieve obtain, anything but from what single a certain strength decide, but from various compound what the resultant force direction of history become by strength decides.
除非有一合力作用于物体上，否则物体的方向是不会发生变化的。
There is no change in the motion of a body unless a resultant force is acting upon it.
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