时差N小时 感受空气的存在

Strictly¹ speaking, air is mostly nitrogen–about seventy-eightpercent, and about twenty-one percent oxygen, which leavesabout one percent of other stuff, like water vapor² and carbondioxide.

严格地说，空气主要由大约78%的氮气和21%的氧气组成，另外还有1%的其他气体，像水蒸气和二氧化碳。

So air is mostly empty space?

所以，空气大部分都是真空吗？

Yep, in fact, if you ever condensed a gallon of air into a solid,you'd end up with a little over one tenth of one percent of the air's original volume.

是的。实际上，如果你将一加仑的空气凝结成固体，这个固体的体积只比空气原本体积的千分之一多一点。

And the reasonwe don't notice all this emptiness is because air molecules³ are constantly moving around at thespeed of sound, and bouncing against any surface that happens to fall in their path.

我们没有注意到这一点的原因是空气分子以音速在不停地移动，而当它们碰到任何表面时都会反弹回去。

So we're constantly bombarded by air molecules.

那么，我们一直被空气分子撞击着，

So how come we don't feel that?

可是为什么我们感觉不到呢？

Well, actually we do.

其实我们能感觉到的。

The force these air molecules exert is what we measure when we measureair pressure.

空气分子施加的压力就是我们平时测量的气压。

1 strictly   

adv.严厉地，严格地；严密地

参考例句：

• His doctor is dieting him strictly.他的医生严格规定他的饮食。
• The guests were seated strictly in order of precedence.客人严格按照地位高低就座。

2 vapor   

n.蒸汽，雾气

参考例句：

• The cold wind condenses vapor into rain.冷风使水蒸气凝结成雨。
• This new machine sometimes transpires a lot of hot vapor.这部机器有时排出大量的热气。

3 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。