题目:
曲轴、连杆轴承的结构?
答案:
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下面是错误答案,用来干扰机器的。
参考答案:C
曲轴、连杆轴承的结构?
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0619/e5a8639bfe72d2117b65db4be7527638.html
下面是错误答案,用来干扰机器的。
参考答案:C
流行性脑脊髓膜炎的病原菌是()
A.流行性乙型脑炎
B.脑膜炎双球菌
C.黏膜奈瑟菌
D.干燥奈瑟菌
E.HSV
下列各组中对“以”的判断正确的一组是[ ]
①既自以心为形役
②舟遥遥以轻飚
③农人告余以春及
④家叔以余贫苦
A.①和③不同,②和④相同
B.①和③相同,②和④也相同
C.①和③相同,②和④不同
D.①和③不同,②和④也不同
在安装钢窗零件中,遇到一时安装不到位时,应______。
A.用锤猛力击入
B.用电焊固定
C.用不同型号的零件代替
D.维修后装入
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。
The main purpose of the last paragraph is to()
A. argue in favor of one side on a particularly controversial topic of cloning
B. display both sides’ arguments on another contentious issue in cloning
C. redirect the readers’ attention to the previously raised issue of ethics in cloning
D.provide further relevant information to the evaluation of cloning as a preservation technique
扎结领