Fortunately, however, ancient men made tools of stone, especially flint,

然而， 幸运的是，远古人用石头制作了工具，特别是用燧石，

because they are unwilling to have their names entered as having taken out such and such a book,

因为它们不愿让人家记下它们公司的名字和借阅的某一本书。

It was not forced upon them by the survival competition; they could have caught and lived on prey without using poison, just as the thousands of non-poisonous snakes still do.

毒液不是生存竞争强加给它们的，它们也可以不用毒液捕捉动物而生存，就像今天成千上万的无毒蛇那样。

Nor is it only the ignorant and ill-educated person who has such faith in the bottle of medicine.

并不只是那些无知和没受过良好教育的人才迷信药瓶子。

To escape from the Earth in a rocket, one must travel at seven miles per second.

要乘坐一枚火箭飞离地球，火箭的速度要达到每秒7英里，

The undulating waves of the open sea are generated by three natural causes:

海浪是由三个自然因素形成的：