能量永远不会产生或消失，这是一条物理定律。它只是从一种能量变成了另一种能量。在我们的例子中， 动能在刹车时转变为热能
A.Energy is never created or lost it's a physics law that it just changes from one kind of energy to another and in our case, motion energy turns into heat energy when we brake. B.It is a law of physics that energy is never produced or destroyed. It just changes from one type of energy into another type. In our example the kinetic energy changes into heat energy during braking. C.Energy is never produced or lost, it's a physical law that it just transfers from one kind of energy to another and in our case, moving energy turns into heat energy when braking.正确答案B
