So archaeologists have neither history nor legends to help them to find out where the first 'modern men' came from.

于是，考古学家们既缺乏历史记载，又无口头传说来帮助他们弄清最早的“现代人”是从哪里来的。

Suppose every sensor gives perfectly accurate readings of temperature,

再假定每个传感器都极端准确地读出了温度、

He no sooner recovers his equilibrium than the next porpoise comes along and hits him another crack.

海龟刚恢复平衡，第二只海豚又冲过来猛击一下。

The slope averages about 1 in 30, but contains steep,

坡度平均约为1/30，但其中包括陡峭的，

therefore the jungles and the savannahs know of no'juvenile delinquency'.

因此，丛林和荒凉地区不知道什么叫青少年犯罪"。

or even the universe itself, must in the nature of things 'wear out'.

甚至宇宙本身，从事物的本质上来说都会磨损掉"。