英语必修三Unit-Astronomy课文翻译

英语必修三

Unit-4-Astronom y

课文翻译

HOW LIFE BEGAN ON THE EARTH

地球上生命的起源

No one knows exactly how the earth began, as it happened so long ago. However, according

to a widely accepted theory, the universe began with a Big Bang that threw matter in all

that, atoms began to form and combine to create stars and other bodies.

没有人确切知道地球是怎么样开始形成的，

因为在很早很在以前地球就形 成了。

然而，

一种普遍

为人们所接受的 理论是：宇宙起源于一次大爆炸，

这次大爆炸将物质投射到四面八方。

< br>然后，

原

子开始形成并结合成恒星和其他天体。

For several billion years after the Big Bang, the earth was still just a cloud of dust. What it

was to become was uncertain until between 4.5 and 3.8 billion years ago when the dust settled into

a solid globe. The earth became so violent that it was not clear whether the shape would last or not.

It exploded loudly with fire and rock. They were in time to produce carbon, nitrogen, water vapour

and other gases, which were to make the earths atmosphere. What is even more important is that

as the earth cooled down, water began to appear on its surface.

大爆炸后好几十亿年过去了，但地球

还只是一团尘埃。随后它会变成什么没人能 知道，直到

38

-

45

亿年前，这团尘埃才慢慢地形成

一个团体的球状物。

地球开始变得激烈动荡，

不知道这个固体形状是否会继续存下去。

它猛烈地

爆炸喷出了烈火与岩石，最终产生了碳，氮气，水蒸气和其他多种气体，

从而形成了地球的大气

层。更为重要的是，地球冷却了下来，地球的 表面就开始出现了水。

Water had also appeared on other planets like Mars but, unlike the earth, it had disappeared

later. It was not immediately obvious that water was to be fundamental to the development of life.

What many scientists believe is that the continued presence of water allowed the earth to dissolve

harmful gases and acids into the oceans and seas. This produced a chain reaction, which made it

possible for life to develop.

在火星这些其他行星上都出现了水，

但 和地球不同的是，

这些水后来都

消失了。水对于生命的发展会起 关键作用，

这一点在当时并不明显。很多科学家相信，

由于地球

上长期有水存在，

使得地球得以把有害气体和酸性物质溶解在海 洋里。

这就产生了一系列的反应，

使得生命就有可能开始发展了 。

Many millions of years later, the first extremely small plants began to appear on the surface

of the water. They multiplied and filled the oceans and seas with oxygen, which encouraged the

later development of early shellfish and all sorts of fish. Next, green plants began to grow on land.

They were followed in time by land animals. Some were insects. Others, called amphibians, were

able to live on land as well as in the water. Later when the plants grew into forests, reptiles

appeared for the first time. They produced young enerally by laying eggs. After that, some huge

animals, called dinosaurs, developed. They laid eggs too and existed on the earth for more than

140 million years. However,65 million years ago the age of the dinosaurs ended. Why they

suddenly disappeared still remains a mystery. This disappearance made possible the rise of

mammals on the earth. These animals were different from all life forms in the past, because they

gave birth to young baby animals and produced milk to feed them.

好几百万年后，水的表面开始出现了极小的植物。他们繁殖起 来就使得早期的海洋充满了氧气，

这为早期的贝类及其他各种鱼类的发育进一步创造了条 件。接着，绿色植物开始出现在陆地上。