其包含了三种情况：作用力与反作用力都不做功；
It contains three situations: both of force and reaction do not work;
语言结构隐含两种基本力：作用力与反作用力，它们分别包括一系列力倾向。
Linguistic structures suggest two types of basic forces: agonist and antagonist that include a series of force tendencies.
答：两个物体之间的作用力与反作用力总是大小相等，方向相反，作用在同一直线上。
The force between two objects and reaction, always also in the same line, equal and opposite direction.
还有一个例子证明作用力,与负反作用力相等。
That's another example where you see action equals minus reaction.
作用力等于反作用力，这是牛顿第三定律，因此Fij与Fji完全相等，但它们方向相反。
Actions equals minus reactions, according to Newton's Third Law, so this force, Fij, will be exactly the same as Fji, except in the opposite direction.
利用作用力做功和反作用力做功的代数和与参照系的选择无关这样的结论，计算质点组的内力作功之和将非常简捷方便。
The sum of work of effect and reaction has nothing to do with the choice of criterion. With this conclusion, it is very easy to work out the sum of particle and work of internal force.
每一种作用力都有一种与之等量的反作用力。
Every kind of input strength has a reverse strength which is as big as it.
每一种作用力都有一种与之等量的反作用力。
Every kind of input strength has a reverse strength which is as big as it.
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