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  3. The topic of cloning has been a politically and ethically controversial one since its very beginning. While the moral and philos

The topic of cloning has been a politically and ethically controversial one since its very beginning. While the moral and philos

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问题     The topic of cloning has been a politically and ethically controversial one since its very beginning. While the moral and philosophical aspects of the issues are entirely up to the interpretation of the individual, the application of cloning technology can be studied objectively. Many in the scientific community advocate the use of cloning for the preservation and support of endangered species of animals, which aside from cloning, have no other practical hope for avoiding extinction.
    The goal of the use of cloning to avoid extinction is the reintroduction of new genes into the gene pool of species with few survivors, ensuring the maintenance and expansion of genetic diversity. Likely candidates for this technique are species known to have very few surviving members, such as the African Bongo Antelope, the Sumatran Tiger, and the Chinese Giant Panda. In the case of Giant Panda, some artificial techniques for creating offspring have already been performed, perhaps paving the way for cloning as the next step in the process.
    With the estimated population of only about 1, 000 Giant Pandas left in the world, the urgency of the situation has led to desperate measures. One panda was born through the technique of artificial insemination in the San Diego Zoo in the United States. "Hua Mei" was born in 1999 after her parents, Hsing-Hsing and Ling-Ling, had trouble conceiving naturally.
    The plan to increase the Giant Panda population through the use of cloning involves the use of a species related to the Giant Panda, the American Black Bear. Egg cells will be removed from female black bears and then fertilized with Panda cells such as those from Ling-Ling or Hsing-Hsing. The fertilized embryo will then re-implanted into the black bear, where it will grow and mature, until a new panda is delivered from the black bear host.
    Critics of cloning technology argue that the emphasis on cloning as a method by which to preserve species will draw funding away from other methods, such as habitat preservation and conservation. Proponents of cloning counter that many countries in which many endangered species exist are too poor to protect and maintain the species’ habitats anyway, making cloning technology the only practical way to ensure that those species survive to future generations. The issue is still hotly debated, as both sides weigh the benefits that could be achieved against the risks and ethical concerns that constantly accompany any argument on the issue.
The main purpose of Paragraph 4 is to
选项 A、detail the process by which cloning in the panda population has been executed in the past.
B、guide the reader to consider the possibility of cloning in restoring the panda population.
C、demonstrate that the use of cloning to repopulate the panda species is a feasible goal.
D、inform the reader of how cloning would be carried out in the panda population.
答案D
解析 主旨题。第四段第一句就是本段中心：通过使用克隆技术来增加大熊猫种群的计划涉及使用另一种与大熊猫有关的物种——美国黑熊。下文是具体的操作过程。由此可见，D项正确。A项错在in the past(过去)的使用，原文描述的是将来的事情(will)。B、C项无法从原文中得到肯定结论。
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