and so the tools of long ago have remained when even the bones of the men who made them have disappeared without trace.

因此，尽管制造这些工具的人的骨头早已荡然无存，但远古时代的石头工具却保存了下来。

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、

Their humbler followers, such as partridges, have a like power of strong propulsion, but soon tire.

次于野鸭和鸽子的鸟，如鹧鸪，有相似的巨大推动力，但很快会疲劳。

as if he were holding it completely enclosed in the hollow of his hand.

就好像完全握在自己手心里一样。

but the scientific dust has long since settled,

但是，自他逝世以来，那场科学上的纷争早已平息了下来，

Those planning a trip to remote areas, or intending to live in countries where drinking water is not readily available, should know about the various possible methods for making water safe.

那些计划去偏远地区旅行，或在饮用水不现成的国家居住的人，应该知道如何使水适于饮用的各种办法。