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英语写作必备例句第971页

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Now move the hand to and fro and around but not up and down.

然后把手前后左右以及旋转摆动，但不要上下摆动。

It will be found that the weight moves but slightly or not at all.

结果会发现，重物是动了，但动得很小，甚至没动。

Imagine a pen attached to the weight in such a way that its point rests upon a piece of paper on the floor.

假定把一支笔拴在重物上，笔尖落在地板上的一张纸上，

Imagine an earthquake shock shaking the floor, the paper, you and your hand.

假定地震发生了，地板、纸、你和你的手都会动，

In the midst of all this movement, the weight and the pen would be still.

重物和笔都却不运动。

But as the paper moved from side to side under the pen point,

由于纸在笔尖下来回运动，

its movement would be recorded in ink upon its surface.

纸的表面就会用墨水记录下地板运动的情况。

It was upon this principle that the first instruments were made,

据这一原理，制造出了最初的地震仪器，

but the paper was wrapped round a drum which rotated slowly.

根但是纸是卷在慢慢旋转的圆筒上的。

As long as all was still, the pen drew a straight line,

只要一切都是静止的，笔就会划出一条直线；

but while the drum was being shaken,

但是，圆筒受到震动，

the line that the pen was drawing wriggled from side to side.

笔所画出的线就会左右摆动。

The apparatus thus described, however,

然而，这里所说的仪器

records only the horizontal component of the wave movement,

记录下来的只是地震波运动中的水平部分，

which is, in fact, much more complicated.

地震波的运动实际比这要复杂得多。

If we could actually see the path described by a particle,such as a sand grain in the rock,

假如我们真能看到的运动轨迹，诸如岩石中一个沙粒分子

it would be more like that of a bluebottle buzzing round the room;

那就像一只嗡嗡叫的绿头苍蝇在屋内飞行的轨迹，

it would be up and down, to and for and from side to side.

呈现出上上下下、来来回回、左左右右3种性质的运动。

Instruments have been devised and can be so placed that all three elements can be recorded in different graphs.

已经设计出了一些仪器，它按照一定的安放方式就可测绘出这三种运动的曲线图。

When the instrument is situated at more than 700 miles from the earthquake centre,

如果把这种仪器安装在距震源700多英里远的地方，

the graphic record shows three waves arriving one after the other at short intervals.

曲线纪录就能显示出前后相间的这3种地震波。

The first records the arrival of longitudinal vibrations.

首先记录下的是纵向波的到达；

The second marks the arrival of transverse vibrations which travel more slowly and arrive several minutes after the first.

然后记录下的是横向波的到达，横向波比纵向波传播得慢，在纵向波到达几分钟后才能到达。

These two have travelled through the earth.

这两种波都是穿过地球而来的。

It was from the study of these that so much was learnt about the interior of the earth.

正是从这两种波的研究中，我们可以了解到地球内部的许多情况。

The third, or main wave,

第三种波，即主波，

is the slowest and has travelled round the earth through the surface rocks.

是最慢的，是围绕地球通过表面岩石传来的。

We must conclude from the work of those who have studied the origin of life,

我们必须从那些研究生命起源的人的工作总结出：

that given a planet only approximately like our own, life is almost certain to start.

如果设想有一颗行星和我们地球的情况基本相似，那几乎肯定会产生生命。

Of all the planets in our own solar system,

在我们太阳系的所有行星中，