问题

纸的最早发明是在(   )  

A.战国时期

B.春秋时期

C.西汉时期

D.东汉时期

答案

答案:C

题目分析:此题是基础题。考查的是学生的秦汉文化相关史实的识记。甘肃天水的一座汉墓里,出土了一张纸。张纸又薄又软,纸面平整光滑,上面有墨绘的山、川、路等,据考证,这是西汉早期用麻做的纸,也是目前世界上已知的最早的纸。所以纸最早发明是在西汉,故答案选择C。

单项选择题 A3/A4型题
单项选择题

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 1000 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. (402 words)

Notes: ethically 道德上。gene pool 基因库。insemination n.受精。fertilize 使受精。embryo 胚胎。proponent支持者,拥护者。weigh A against B权衡A和B的利弊。

It can be inferred from the information given in the text that the best candidate for cloning would be()

A. Giant Pandas

B. an endangered species with many living related species

C. the species in which previous techniques of artificial reproduction have been successfully applied

D. those for which cloning is the only feasible method by which to reproduce the species