Scientists have developed a water treatment system that they say is a powerful but simple way to save lives. Four grams of chemicals can treat ten liters of dirty water for a low cost, about ten cents 题目和参考答案——青夏教育精英家教网—

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Scientists have developed a water treatment system that they say is a powerful but simple way to save lives. Four grams of chemicals can treat ten liters of dirty water for a low cost, about ten cents.

Experts say infections from dirty water kill several thousand children in developing countries every day. The Procter and Gamble company has been developing the "PUR Purifier of Water" system since 1995. The company has been working with the United States Centers for Disease control and Prevention(C.D.C.).

C.D.C. researchers tested it in Guatemala, Pakistan and Kenya. Procter and Gamble researcher Greg Allgood says cases of diarrhea(腹泻) in those studies fell by about 50 percent. Researchers from Johns Hopkins University in Maryland tested the system at a refugee camp in Liberia. Mr. Allgood says that study found a reduction of more than 90 percent. Use of the system is being expanded worldwide.

The treatment contains bleach(漂白剂) to kill disease-causing organisms. It also contains something that dirt and other particles stick to. Mr. Allgood says the chemicals can remove lead and other dangerous metals and even agricultural poisons like D.D.T.

Mr. Allgood heads the Children's Safe Drinking Water program at Procter and Gamble. He says about forty million packets of the treatment have been given to countries for free. They have been used in emergencies and in areas with limited supplies of clean water.

Clean water is a limited resource in many parts of the world. Delegates from about 130 nations attended the Fourth World Water Forum last month in Mexico City. Scientists, policy experts and others discussed ways to provide clean water to the world’s poor. Organizers say more than twenty percent of the world population lacks clean drinking water. The final declaration did not go so far as to declare water a human right. But it did say that governments, not private companies, must take the lead in improving the public’s ability to have clean water.

46. What is mainly talked about in this passage?

A. Water pollution around the world.

B. The causes of diarrhea in African countries.

C. A newly developed water treatment system.

D. The Fourth World Water Forum in Mexico City.

47. Which of the following developed the water treatment system?

A. The US Centers for Disease Control and Prevention.

B. The Procter and Gamble Company and C.D.C.

C. The Children’s Safe Drinking Water Program.

D. Johns Hopkins University.

48. Which of the following about the new water treatment system is NOT true?

A. It is effective but very expensive.

B. It was tested in Guatemala, Pakistan and Kenya.

C. It is being expanded worldwide.

D. It can remove dangerous metals in the water.

49. Which of the following shows that the shortage of clean water is a serious problem?

A. Forty million packets of the treatment have been given to countries for free.

B. Delegates from about 130 nations attended the Fourth World Water Forum.

C. Four grams of chemicals can treat liters of dirty water for a low cost.

D. Infections from dirty water kill several thousand children every day.

50. The best title for this article is ______.

A. A Small Packet of Chemicals, a Big Effect on Dirty Water

B. The Procter and Gamble Company and C.D.C.

C. The Shortage of Clean Water

D. How to Cure Diarrhea

【小题1】C

【小题2】B

【小题3】A

【小题4】D

【小题5】A

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Batteries can power anything from small sensors to large systems. While scientists are finding ways to make them smaller but even more powerful, problems can arise when these batteries are much larger and heavier than the devices themselves. University of Missouri(MU) researchers are developing a nuclear energy source that is smaller, lighter and more efficient.

“To provide enough power, we need certain methods with high energy density(密度)”，said Jae Kwon, assistant professor of electrical and computer engineering at MU. “The radioisotope(放射性同位素) battery can provide power density that is much higher than chemical batteries.”

Kwon and his research team have been working on building a small nuclear battery, presently the size and thickness of a penny, intended to power various micro / nanoelectromechanical systems (M/NEMS). Although nuclear batteries can cause concerns, Kwon said they are safe.

“People hear the word ‘nuclear’ and think of something very dangerous,” he said, “However, nuclear power sources have already been safely powering a variety of devices, such as pace-makers, space satellites and underwater systems.”

His new idea is not only in the battery’s size, but also in its semiconductor(半导体). Kwon’s battery uses a liquid semiconductor rather than a solid semiconductor.

“The key part of using a radioactive battery is that when you harvest the energy, part of the radiation energy can damage the lattice structure(晶体结构) of the solid semiconductor,” Kwon said, “By using a liquid semiconductor, we believe we can minimize that problem.”

Together with J. David Robertson, chemistry professor and associate director of the MU Research Reactor, Kwon is working to build and test the battery. In the future, they hope to increase the battery’s power, shrink its size and try with various other materials. Kwon said that battery could be thinner than the thickness of human hair.

Which of the following is true of Jae Kwon?

A. He teaches chemistry at MU.

B. He developed a chemical battery.

C. He is working on a nuclear energy source.

D. He made a breakthrough in computer engineering.

Jae Kwon gave examples in Paragraph 4_________.

A. to show chemical batteries are widely applied.

B. to introduce nuclear batteries can be safely used.

C. to describe a nuclear-powered system.

D. to introduce various energy sources.

Liquid semiconductor is used to _________.

A. get rid of the radioactive waste

B. test the power of nuclear batteries.

C. decrease the size of nuclear batteries

D. reduce the damage to lattice structure.

According to Jae Kwon, his nuclear battery _______.

A. uses a solid semiconductor

B. will soon replace the present ones.

C. could be extremely thin

D. has passed the final test.

The text is most probably a ________.

A. science news report B. book review

C. newspaper ad D. science fiction story

PART FOUR WRITING (45%)

The fact has worried many scientists ______ the earth is becoming warmer and warmer these years.

A. what B. which C. that D. though

People diet to look more attractive. Fish diet to avoid being beaten up, thrown out of their social group, and getting eaten as a result. That is the fascinating conclusion of the latest research into fish behavior by a team of Australian scientists.

The research team have discovered that subordinate fish voluntarily diet to avoid challenging their larger competitors. “In studying gobies we noticed that only the largest two individuals, a male and female, had breeding(繁殖) rights within the group," explains Marian Wrong. “All other group members are nonbreeding females, each being 5-10% smaller than its next largest competitor. We wanted to find out how they maintain this precise size separation."

The reason for the size difference was easy to see. Once a subordinate fish grows to within 5-10% of the size of its larger competitor, it causes a fight which usually ends in the smaller goby being driven away from the group. More often than not, the evicted fish is then eaten up.

It appeared that the smaller fish were keeping themselves small in order to avoid challenging the boss fish. Whether they did so voluntarily, by restraining how much they ate, was not clear. The research team decided to do an experiment. They tried to fatten up some of the subordinate gobies to see what happened. To their surprise, the gobies simply refused the extra food they were offered, clearly preferring to remain small and avoid fights, over having a feast.

The discovery challenges the traditional scientific view of how boss individuals keep their position in a group. Previously it was thought that large individuals simply used their weight and size to threaten their subordinates and take more of the food for themselves, so keeping their competitors small.

While the habits of gobies may seem a little mysterious. Dr. Wong explains that understanding the relationships between boss and subordinate animals is important to understanding how hierarchical(等级的) societies remain stable.

The research has proved the fact that voluntary dieting is a habit far from exclusive to human.”As yet, we lack a complete understanding of how widespread the voluntary reduction of food intake is in nature," the researchers comment. “Data on human dieting suggests that, while humans generally diet to improve health or increase attractiveness, rarely does it improve long-term health and males regularly prefer females that are fatter than the females' own ideal."

65 When a goby grows to within 5-10% of the size of its larger competitor, it ______.

A. faces danger B. has breeding rights

C. eats its competitor D. leaves the group itself

66. The underlined words “the evicted fish" in Paragraph 3 refer to _____.

A. the fish beaten up B. the fish found out

C. the fish fattened up D. the fish driven away

67 The experiment showed that smaller fish ____.

A. fought over a feast B. went on diet willingly

C. preferred some extra food D. challenged the boss fish

68. What is the text mainly about?

A. Fish dieting and human dieting.

B. Dieting and health.

C. Human dieting.

D. Fish dieting.

What makes a person a scientist? Does he have ways or tools of learning that are different from those of others??The answer is“no”.It isn't the tools a scientist uses but how he uses these tools which makes him a scientist .You will probably agree that knowing how to use a power is important to a carpenter（木匠）.You will probably agree,too, that knowing how to investigate（调查）,how to discover information ,is important to everyone. The scientist ,however ,goes one step further ;he must be sure that he has a reasonable answer to his questions and that his answer he gets to many questions is into a large set of ideas about how the world works.?

The scientist's knowledge must be exact .There's no room for half right or right just half the time. He must be as nearly right as the conditions permit .What works under one set of conditions at one time must work under the same conditions at other times. If the conditions are different ,any changes the scientist observes in a demonstration（实证）must be explained by the changes in the conditions. This is one reason why investigations are important in science .Albert Einstein ,who developed the Theory of Relativity ,arrived at this theory through mathematics. The accuracy（正确性）of his mathematics was later tested through investigation. Einstein's ideas were proved to be correct .A scientist uses many tools for measurements .Then the measurements are used to make mathematical calculations（计算）that may test his investigations.

1.What makes a scientist according to the passage??

A.The tools he uses.

B.His ways of learning.?

C.The way he uses his tools.

D.The various tools he uses.?

2.“...knowing how to investigate ,how to discover information ,is important to everyone.”The writer says this to show_______.?

A.the importance of information

B.the difference between scientists and ordinary people?

C.the importance of thinking

D.the difference between carpenters and ordinary people?

3.A sound scientific theory should be one that_______.?

A.works under one set of conditions at one time and also works under the same conditions at other times?