They may also have used wood and skins, but these have rotted away.

他们也可能用过木头和兽皮，但这类东西早已腐烂殆尽。

One is the general atmosphere of secrecy in which it is carried out,

一是科研工作中普遍存在的保密气氛；

People woken during these periods of eye-movements generally reported that they had been dreaming.

在眼球活动期间被叫醒的人都说自己在做梦；

then at the height of his military success in the Thirty Years' War,had dictated her measurements and armament.

正处在"三十年战争"的军事鼎盛阶段，他亲自规定了这艘船的规模和武器配备。

who put his questions to nature instead of to the ancients,

他向自然界而不是向古人提出问题，

the writer comes to discern things in his material which were not consciously in his mind when he began.

会领悟到素材中很多东西是他刚动笔时所未意识到的。