Scientists have confirmed that the majority of overweight people who try to lose weight either by cutting calories or exercising will return to their former size．Fewer than 10 percent of the l2 milli 题目和参考答案——青夏教育精英家教网—

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Scientists have confirmed that the majority of overweight people who try to lose weight either by cutting calories or exercising will return to their former size．Fewer than 10 percent of the l2 million British people who go on a diet each year succeed in losing significant amounts of weight and most of those who do put it all back on again within a year．

The study of 25，000 people provides further evidence of the popularity of‘yo-yo dieting’where slimmers get into a cycle of losing weight and regaining it．The scientists，from the Medical Research Council’s National Survey of Health and Development，have concluded it is better to avoid getting fat in the first place．They followed 5，362 men and women from their birth in l946 and 20，000 from birth in l958，measuring their weight and blood pressure and assessing their lifestyles．The researchers found both groups began gaining weight in the 1980s and have steadily increased in size ever since．

Dr Rebecca Hardy，the council’s programme leader on body size，said：“0nce people become, overweight，they continue extremely upwards．They hardly ever go back down．A(印刷不清两个单词) weight but very few get back to normal。The best policy is to prevent people becoming overweight．For men weight goes up steadily through life。For women it starts slowly and accelerates in the mid-thirties．”

But the study's findings do not mean dieting is pointless，as eating less and taking more exercise can increase fitness and lower blood pressure．In 2009，a quarter of adults and l4 percent of children were obese(过度肥胖的)，according to the Department of Health’s latest Health Survey for England．Although previous research has shown one in four Britons is trying to lose weight at any one time，it has been predicted that 60 percent of us will be obese by 2050，leading to even more cases of diabetes(糖尿病)，heart disease and cancer．Experts said we are programmed to put on weight rather than lose it．Dieting can make this tendency worse as decreasing calorie intake causes the body to go into starvation mode and reduce the amount of energy it naturally expends，making it even harder to lose weight．Commenting on the study，Professor Nick Finer from London Hospital，said：“It is unlikely that man would have progressed with mechanisms to fight against obesity which has only become a problem in the last 30～40 years．For most of human history，storing fat would have been an advantage．”

47．According to Dr Rebecca Hardy，which of the following is TRUE?

A．It is easier for men to lose weight than women．

B．Once people lose weight，they never put on weight again．

C．Never to become fat is the best way of keeping a good shape．

D．The fact that fat people keep their weight upwards is unusual．

48．The author says “the study’s findings do not mean dieting is pointless” because ．

A．the study lacks believable facts

B．obese people are confident in losing weight

C．dieting can really make a few people lose weight

D．dieting and sports help to keep people free from some diseases

49．From the last paragraph，we can learn that ．

A．decreasing calorie intake makes it even harder to lose weight

B．the idea that people lose weight with mechanisms is practical

C．being overweight is a lasting problem through the human history

D．by 2050 more and more people will have got unfit because of losing weight

50．Which of the following can serve as the best title of the passage?

A．Which is better：cutting calories or exercisin97

B．Fat people can’t really keep the weight off

C．A new study on people’s health

D．How to go on a healthy diet

C D A B

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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?