Unit 2 Cloning
阅读理解组块专练——练速度
(限时：35分钟)
Ⅰ.阅读理解
A
We are all fascinated by mysteries. To some extent we love to expect strange phenomenon occurring before us. Here are some amazing unsolved mysteries.
The Georgia Guidestones
On one of the highest hilltops in Elbert County, Georgia stands a giant granite monument (花岗岩纪念碑). Carved in eight different languages on the four giant stones are 10 Guides.
The origin of this strange monument is covered in mystery because no one knows the true identity of the man, or men, who constructed it. All we know is that in June 1979, a man identifying himself as R．C.Christian announced that he would build something to convey a message to mankind, but to date, no one knows who R．C.Christian really was.
Bermuda Triangle
The Bermuda Triangle is a triangular area of the Atlantic Ocean. Many planes, ships, and boats are said to have disappeared in this triangle without a trace, which led to the belief that “supernatural” forces exist in this area of the sea.
Could there truly be an unnatural force at work in this geographical triangle or are these disappearances merely coincidence? Either way, numerous people remain unwilling to step over the boundary line into the Devil’s Triangle.
Loch Ness Monster
The Loch Ness Monster is a legendary animal that supposedly lives in the depths of Loch Ness, a long narrow lake located in rural Scotland.
Stories concerning the monster date back to the 6th century AD. Over the years thousands have reported seeing a long neck appearing from the water with a small head of an unknown creature. Pictures have even been taken of this “creature”， but most scientists refuse to believe any creature of this kind lives in the Loch Ness. So far, the evidence is inadequate, and the controversy continues. 语篇解读：本文是一篇说明文。文章主要介绍了世界上三大未解之谜，包括佐治亚州的巨石阵、百慕大三角和尼斯湖水怪。 1．Why is the Georgia Guidestones mysterious?
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A．It is on one of the highest hilltops in Elbert County. B．There are eight different languages on the stones. C．The person who built it remains unknown.
D．R. C. Christian could convey a message to mankind.
解析：选C 细节理解题。根据The Georgia Guidestones部分第二段内容可知，巨石阵很神秘是因为没有人知道是谁建造了它。故选C。
2．Why are people unwilling to enter the Bermuda Triangle? A．It is too remote from land.
B．The chance of surviving is slim there. C．There are supernatural forces in the area. D．All transportations have disappeared there.
解析：选B 推理判断题。根据Bermuda Triangle部分第一段第二句可知，在百慕大三角经常有飞机、轮船和小船失踪；由此可推知，在百慕大三角人们幸存的可能性很小，所以许多人不愿意进入百慕大三角地带。故选B。
3．What can we know about Loch Ness Monster? A．It existed in the 6th century AD.
B．It is said to have a long neck and a large head. C．It has been living in Loch Ness Lake for a long time. D．People haven’t reached an agreement on its existence.
解析：选D 细节理解题。根据最后一段第一句可知，关于水怪的故事始于公元6世纪，并不是说水怪出现在公元6世纪，故排除A项；根据最后一段第二句中的“with a small head”可知，B项错误；根据最后一段倒数第二句可知，大多数科学家都不相信有这种水怪生活在尼斯湖中，故排除C项；根据最后一段最后一句可知，D项“人们对它的存在没有达成一致意见”符合原文。故选D。
B
Have you seen Jurassic Park? In this film, scientists use DNA kept for tens of millions of years to clone dinosaurs. They find trouble, however, when they realize that the cloned creatures are smarter and more dangerous than expected. That’s nothing more than a fiction.
But could we really clone endangered animals?
To date, the most successful attempt to do so was the cloning of a gaur, a rare ox-like animal from southeast Asia. Scientists used a cow to bring the cloned baby gaur, named Noah. Two days after birth, however, Noah died from a common bacterial infection.
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Other endangered species that may be cloned include the African bongo antelope (羚羊), the Sumatran tiger, the cheetah (猎豹), and the giant panda.
Next, could we really clone extinct animals?
In theory? Yes. To do this, you need a well-kept source of DNA from the extinct animals such as wool mammoth (毛象), Tasmanian tiger, or even dinosaur, and a closely related species, still living, which could serve as a_surrogate_mother.
In reality? Probably not. On the one hand, it’s not likely that extinct animals’ DNA could survive undamaged for such a long time. Cloning such extinct animals as wool mammoth, Tasmanian tiger, or dinosaur is much more difficult due to the lack of properly well-preserved DNA. On the other hand, for example, a gaur can have a cow as a surrogate mother, definitely not a monkey. But what about an extinct animal as unique as the panda? What species could possibly serve as a surrogate mother?
Cloning presents many exciting possibilities. However, even if extinct animals were brought back, they could not survive in today’s world. Not only do most extinct animals have no habitat to live in, but the other plants and animals they depended on for food may also be gone as well.
语篇解读：本文说明了在克隆灭绝动物的过程中遇到的重重困难与障碍。即使克隆成功了，其赖以生存的栖息地和食物链也已经被破坏，被克隆出来的动物也无法继续生存下去。 4．It can be learned from the text that ________. A．the gaur is an extinct species
B．the gaur lives in Asia and is endangered
C．scientists have cloned the African bongo antelope D．both the cheetah and the giant panda live in Asia
解析：选B 细节理解题。根据第二、三段可知，印度野牛生活在亚洲的东南部，濒临灭绝。
5．The underlined words “a surrogate mother” in Paragraph 5 probably refer to a female who ________.
A．gives birth to a baby of its own B．cannot give birth to a baby
C．gives birth to a baby for another female D．provides DNA
解析：选C 词义猜测题。根据第五段的描述可知，此处表示的是，把一种动物的DNA提取出来之后，在另外一种动物的体内进行胚胎繁殖，而这种动物就被称为a surrogate mother，由此判断，画线部分意思为“代孕妈妈”，故C项正确。
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6．The difficulty in cloning an extinct species is the lack of ________. A．both the well-preserved DNA and a surrogate mother B．both the habitat to live in and the well-preserved DNA C．both the well-preserved DNA and plants to live on D．both the habitat to live in and plants to live on
解析：选A 细节理解题。根据文章倒数第二段中的“On the one hand ... On the other hand ...”两个方面的表述可知，克隆的困难在于一是要寻找灭绝动物的保存完好的DNA，二是要寻找到合适的代孕的物种，故A项正确。
7．In the author’s opinion, it is possible that ________. A．all the extinct species may be cloned
B．extinct species may be cloned and easily survive C．a gaur can have a monkey as a surrogate mother D．some extinct species may be cloned, but not survive
解析：选D 推理判断题。本文作者客观叙述了在克隆灭绝动物过程中所存在的种种困难与障碍。根据最后一段的表述可知，也许克隆存在众多的可能性，但是即使克隆成功了，也许会由于其赖以生存的栖息地和食物链已经灭绝而无法继续存活下去。由此判断D项正确。
C
Plant cloning has been an agricultural technique used by farmers and gardeners for centuries. Grafting (嫁接) is a common form of plant cloning. Many plants in nature actually clone themselves and reproduce asexually (无性生殖地)．
Cloned plants are much more predictable than normal plants, so their yield (产量) is more reliable. Cloned plants also reproduce faster, limiting the amount of time between planting
and harvesting. It is also often cheaper to produce seeds through cloning than through traditional methods. Plants can essentially be optimized so that farmers or individual growers always have the best seeds available. With higher yield at a faster rate, farms can produce more food for more people while decreasing overall costs.
Cloning can be used to wipe out diseases that previously killed off entire fields of crops. This would make plants immune to the kinds of diseases that farmers and gardeners around the world fear each year. Crop failures due to disease and virus could become a thing of the past. Also, plants that are near extinction can be brought back to life through cloning.
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Through cloning scientists can develop super fruits and vegetables of superior (更好的) nutritional quality. This could make for a healthier population overall. This has already been done through selective pollination (授粉), and genetic cloning could take it to the next level.
By plant cloning we have a population of identical plants and all these plants equally suffer from the same diseases, but in nature the weak would die and the strong would survive. While there are some dangers to consider with plant cloning, there are plenty of benefits that could prove vital to the propagation (繁衍) of the human species.
语篇解读：本文是说明文。文章主要介绍了植物克隆的好处。
8．The underlined word “optimized” in Paragraph 2 is closest in meaning to “________”．
A．grown C．perfected
B．produced D．examined
解析：选C 词义猜测题。根据“so that farmers or individual growers always have the best seeds available”可知，optimize与perfect的意思相近。
9．According to the text, cloned plants ________. A．have lower yield than normal plants B．need less care from people C．prevent various kinds of diseases D．have a shorter growth cycle
解析：选D 细节理解题。从第二段中的“Cloned plants also reproduce faster, limiting the amount of time between planting and harvesting.”可知，克隆的植物的生长周期短。
10．What can we infer from the text?
A．The fruits produced by cloned plants taste much better. B．There are more cloned plants than normal plants now. C．Plant cloning can disturb the laws of nature. D．People should avoid eating cloned fruits.
解析：选C 推理判断题。从最后一段中的“By plant cloning we have a population of identical plants and all these plants equally suffer from the same diseases, but in nature the weak would die and the strong would survive.”可知，克隆会破坏自然界的规律。
11．What is the main purpose of the text?
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