If you can keep your body horizontal when you swim, you create a lot less drag, and all.
如果你在游泳的时候能够保持身体的水平，那么你划臂就会省力的多，而且全部的力量都可以用来推动。
If you can keep your body horizontal when you swim, you create a lot less drag, and all your energy can be used to send you forward.
如果你在游泳的时候能够保持身体的水平，那么你划臂就会省力的多，而且全部的力量都可以用来推动你向前。
Some movements involving primarily vertical or horizontal motions of the body as a whole, in which rotations can be ignored, can be studied using simple equations of linear motion in three dimensions.
有些运动主要涉及整体的垂直或水平运动，其中转动可以忽略，可以用三维线性运动的简单方程来研究。
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