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  3. Humanity is a new experiment on planet Earth. For most of its history, life on Earth was restricted to the sea. Living things be

Humanity is a new experiment on planet Earth. For most of its history, life on Earth was restricted to the sea. Living things be

admin2008-12-30  59
问题     Humanity is a new experiment on planet Earth. For most of its history, life on Earth was restricted to the sea. Living things began to populate the land slightly over 400 million years ago. And humans have existed for no more than 3 million years.
    One way to represent the evolution of life is to compress the 4. 6-billion-year history of Earth into a 1-year-long film. In such a film, Earth forms as the film begins on January 1, and through all of January and February it cools and is cratered(变成坑状) and the first oceans form. But those oceans remain lifeless until sometime in March or early April, when the first living things develop. The 4-billion-year history of Precambrian (前寒武纪) evolution lasts until the film reaches mid-November, when primitive ocean life begins to evolve into complex organisms such as trilobites(三叶虫).
    If we examine the land instead of the oceans, we find a lifeless waste. But once our film shows plant and animal life on the land, about November 28, evolution proceeds rapidly. Dinosaurs, for example, appear on about December 12 and vanish by Christmas Eve, as mammals (哺乳动物) and birds flourish.
    Throughout the 1 -year-run of our film there are no humans, and even during the last days of the year as the mammals rise and dominate the landscape, there are no people. On the early evening of December 31, vaguely human forms move through the grasslands, and by late evening they begin making stone tools. The Stone Age lasts until about 11:45 p. m. , and the first signs of civilization, towns and cities, do not appear until 11:54 p. m. The Christian era begins only 14 seconds before the New Year, and the Declaration of Independence is signed with one second to spare.  
According to the passage, primitive ocean life begins to evolve into complex organisms
选项 A、in the middle of December
B、when Earth is cratered
C、at the beginning of November
D、when the land is still a lifeless waste
答案D
解析 第三段和第四段第一句话就是题目的依据：海洋生命进化为复杂的有机体是在“mid-November”，那时陆地还是一片荒芜。
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