A sound made by tapping on the hull of a ship will be reflected from the sea bottom,

敲打船体所发了的声音会从海底传回来，

the bank must recognize its customer's signature.

因为银行有责任辩认出其储户的签名。

Although mankind has undergone no general improvement in intelligence or morality, it has made extraordinary progress in the accumulation of knowledge.

虽然人类有智力和道德上没有得到普遍提高，但在知识积累方面却取得了巨大的进步。

This continental slope usually starts at a place somewhere near the 100-fathom mark

一般是从差不多100英寻水深的地方开始的，

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"。

Once waves have been generated,

一旦波浪形成，