He was constantly on the move, drawing the Danes after him.

他的部队不停地移动，牵着敌人的鼻子，让他们跟着跑。

since ground stations and satellites cannot see everywhere.

因为地面工作站和卫星不可能看到地球上的每一个地方。

In the conversion of saliva into poison, one might suppose that a fixed process took place.

人们可能认为，唾液转变成毒液，其中有固定的程序。

he identifies himself with its centre of gravity, its mass, its weight;

他把自身和物体重心、质量、重量融为一体。

later, we shall undergo a progressive loss of our vigour and resistance which, though imperceptible at first,

再迟一些，我们就要经历生命力和抵抗力逐步衰退的过程。虽然这个过程起初难以觉察，

Rays from the sun excite and energize the atmosphere of the earth,

太阳光刺激了地球的大气层，并给予它能量；