我们怎么知道的？我们有时在地下深处找到它们的骨骼。

　　When I was a schoolboy in Vienna I used to visit the Natural History Museum,

　　当我在维也纳上小学的时候，我经常参观自然历史博物馆，

　　where I loved to gaze at the great skeleton of a creature called a Diplodocus.

　　在那里我喜欢注视一种叫做恐龙的生物的骨骼。

　　An odd name, Diplodocus. But an even odder creature.

　　一个奇怪的名字，恐龙。但是这却是一种更为奇怪的动物。

　　It wouldn't fit into a room at home or even two, for that matter.

　　它在一间房间里放不下，在两间房间里也放不下。

　　It was as tall as a very tall tree, and its tail was half as long as a football pitch.

　　它像很高的大树一样高，有条半个足球场那样长的尾巴。

　　What a tremendous noise it must have made, as it munched its way through the primeval forest!

　　它啃遍原始森林时，一定怪吵闹的！

　　But we still haven't reached the beginning.

　　可是这也并不是起源。

　　It all goes back much further thousands of millions of years.

　　也还可以从那儿再向前追溯，追溯到数十亿年以前。

　　That's easy enough to say, but stop and think for a moment.

　　这说起来容易，可是你想一想。

　　Do you know how long one second is?

　　你知道，1秒钟有多长？

　　It's as long as counting: one, two, three. And how about 1,000 million seconds? That's 32 years!

　　跟你数1、2、3一样长。10亿秒钟有多长？32年！