argument50 ---欢迎排砖，先谢过了:)

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Argument50  第1篇 让砖头来得更猛烈些吧！
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作者：寄托家园作文版普通用户     共用时间：30分3秒     371 words
从2005年7月10日9时25分到2005年7月10日9时30分
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From a draft textbook manuscript submitted to a publisher.
'As Earth was being formed out of the collision of space rocks, the heat from those collisions and from the increasing gravitational energy of the planet made the entire planet molten, even the surface. Any water present would have evaporated and gone off into space. As the planet approached its current size, however, its gravitation became strong enough to hold gases and water vapor around it as an atmosphere. Because comets are largely ice made up of frozen water and gases, a comet striking Earth then would have vaporized. The resulting water vapor would have been retained in the atmosphere, eventually falling as rain on the cooled and solidified surface of Earth. Therefore, the water in Earth's oceans must have originated from comets.'
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The argement at first sight seems to be well-organized and logically reasoned, but the
author failed to include all the possibilities which would probably contribute to the
formation of the ocean on the earth.

Just as the arguer said, Earth initialized in the form of space rocks collision and during that period, the temperature of the whole planet was extremely high, even on the surface of it. But was it still in the same situation when it cool down and gradually shaped to its size like nowadays? Maybe and maybe not. In the assumption that the temprature was not above 100 degrees centigrade when it approched to the current size, the comets would not be vaporized when it striked Earth. On the other hand, as the general knows, that the vaporation of the comets or the other outer-space objects is due to the friction with the atmosphere but not to the high temprature of the land surface. And whether the atmosphere existed during the formation time of the earth is unknown.

So the water in the current ocean may not come from the comets that striked the planet but other possibilities. For instance, is it only comets which can bring water to our planet? Other objects, such as small planets and meteors, will also be the sources of the water. And we should never ignore the possible chemical reactions that happened on our world stops no time. One of the most common production of the natural chemical reactions is water. It is possibly the severe reactions on the earth which formed the large quantity of water in the oceans.

Another question should be take into consideration in my personal opinion that whether the quantity of water brought to the earth, if there is any, is sufficient enough to form the ocean which covers three forth of the current surface of our planet now? Perhaps it is just one of the many resources that accomplish such great project.

In sum, the argument that the ocean on the earth is formed by the water which is brought by the outer-space comets is not convicing for the arguer failed to include other possibe means of the water that may be beneficial to the same result.

[ Last edited by staralways on 2005-8-10 at 14:25 ]