positive energy theorem

例句：

1. 1. The positive energy theoremstates that the sum of all forces ina system is always zero.
   正能定理表明，一个系统中所有力的和总是零。
2. 2.The positive energy theorem has been provento be accurate in many practical applications.
   正能定理在许多实际应用中已被证明是准确的。
3. 3. The positive energy theorem has beenused to explain the behavior of various materialsand systems.
   正能定理被用来解释各种材料和系统的行为。