特别广播英语第 76 课：You Have a Choice 你可以选定一种解释-2

There are thus two possible explanations to account for the change in speed, but we don't know which one is right. 因而对于车速的改变就可能有两种不同的解释，但是我们不知道哪一种解释是对的。

Furthermore, regardless of which explanation we choose, the end result will be the same: the other train will arrive at the station first. 进一步来说，不管我们选定了上述两种解释中的哪一种，反正最终的结果是同样的：另一列火车将首先抵达终点站。

So it makes no difference whether we say that the other train increased its speed or that our train decreased its speed. 所以，不论我们说另一列火车加快了车速，还是说我们所乘的火车减慢了车速，实际上这两种说法没有什么 区别。

Since both explanations lead to the same result, you can choose either one. 既然上述两种解释会导致同样的结果，那么你选定任何一种解释都可以。

Whenever two things are relative, you can choose either one of them. 不论任何时候，只要两件事物两种情况是相对的，那你就可以选定其中一种解释。

The converse is also true: whenever you have a choice between two things that are equally possible, then the things are relative. 逆真理亦真，每当你从有同样可能的两件事物中选定其中之一时，那么这两种事物之间就是相对的。

There is no reason, except convenience, for choosing one explanation over the other. 除为了方便这个理由而外，我们选定了一种解释而不选另一种解释根本就没有其他别的原因。

The relative speed between the trains remains the same, 10 mph; and the end result will be the same. 如果两列火车之间的相对速度依然相同，都是每小时10英里，那么最终的结果也会是相同的。

Now let's suppose that both trains are at the railroad station loading and unloading passengers and baggage. 现在我们假设两列火车都在火车站上在上下乘客或装卸行李。

A half-hour passes. As we look at the other train through our window, we see that our train seems to start moving, smoothly and slowly. 过了半小时以后，当我们透过车窗看另一列火车时，我们看到我们所乘的火车好像是在缓慢地平稳地开始开动了。