英语必修三unit4POST-READING
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人教版英语必修三第四单元课文翻译人教版英语必修三第四单元课文翻译Unit 4Reading地球上生命的起源没有人确切知道地球是怎样开始形成的,因为在很早很早以前它就形成了。
然而,一种普通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。
然后,原子开始形成并结合成恒星和其他天体。
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固体的球状物。
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在下去。
它(地球)猛烈的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。
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。
水会对生命的发展起关键作用,这一点在当时并不明显。
很多科学家相信,由于地球表面上长期有水存在,它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。
好几百万年以后,水的表面开始出现了极小的植物。
它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,绿色是植物开始出现在陆地上。
随后,陆地上出现了动物,其中有一些是昆虫,另外一些叫两栖动物,它们一般是通过孵蛋而繁衍后代的。
再后来一些叫做恐龙的巨型动物出现了。
它们也生蛋,在地球上生存了一亿四千多年。
然而,六千五百万年前,恐龙时代结束了。
它们为什么会突然灭绝至今仍是个谜。
恐龙的灭绝使地球上哺乳动物的产生有了可能。
哺乳动物不同于以往所有的生物形式,因为它们能从体内生产出幼仔并给幼仔哺乳。
最后,大约260万年前,一些小巧聪明、长着手脚的动物出现了,它们散布在地球的各个地方。
于是,他们接着成为了这个行星上最重要的动物。
然而,他们对地球却并不怎么在意。
它们把过多的二氧化碳释放到大气层中,这使得地球上的热不能释放到太空中去。
TOPIC READINGThe International Space Station国际空间站是在国际合作基础上建造的最大载人空间站,为人类进行科学研究和天文观测提供了技术保障。
The International Space Station (ISS) will be a little “city in space”orbiting (沿轨道运转) 250 miles above the earth. About the size of two football fields, the space station will be a place where people from around the world can live and study in space over long periods of time. The ISS is an extremely expensive project, but it will someday serve as a stepping-stone for future space exploration.Sixteen countries from around the world are working together on the International Space Station. These international partners are the United States, Russia, Canada, Japan, Brazil and European Space Agency (Belgium, Britain, Denmark, France, Germany, Italy, the Netherlands, Norway, Spain, Sweden, and Switzerland).Risking the dangers of space, the sixteen countries are spending billions of dollars and many years building the space station because they believe they can benefit a lot from it. Perhaps the most important benefit is that the space station allows humans to live and study for long periods in microgravity (微重力), or a “weightless”environment.Think of the space station as a stepping-stone to the stars. If humans are ever going to travel to other planets, such as Mars, we must understand the effects of such long journeys on the human body. We’ve learned from past space travel that living in microgravity leads to the weakening of bones and muscles. The space station will allow scientists to understand these effects and study possible solutions for long-term space travel.But studying in microgravity is not the only reason for the space station. For the first time, we will be able to observe the earth from different angles (角度) over long periods of time. The space station will allow us to watch changes in the environment to better understand our own planet. The space station will also give us an opportunity to study the environment of space.Answer the following questions.1. Why do the sixteen countries spend a lot of money building the International Space Station?2. What is the effect of living in microgravity on human bodies?Keys:1. Because they believe the benefits of the station will be great.2. It leads to the weakening of bones and muscles.。