A new study says one part of the human brain may become smaller as the result of a condition known as jet lag. Jet lag results from flying long distances in an airplane. People with jet lag feel extremely tired for several days. They may also have problems in thinking clearly and remembering.

Recently a researcher at the University of Bristol in Britain reported the findings of his jet lag study, which involved twenty women who worked for international airlines. They had served passengers on airplanes for five years. These flight attendants flew across many countries and at least seven time zones. In the study, the flight attendants had different amounts of time to recover from jet lag. Half the women spent five days or fewer in their home areas between long flights. The other half spent more than fourteen days in their home areas.

The researcher took some saliva from the women’s mouths to measure levels of a hormone  (荷尔蒙 ) that increases during stress . He tested them to see if they could remember where black spots appeared on a computer screen .And he took pictures of their brains to measure the size of the brain’s temporal lobes. (脑叶).

It was found that the women who had less time between flights had smaller right temporal lobes. This area of the brain deals with recognizing and remembering what is seen. The same group performed worse and had slower reaction times on the visual memory test. And their saliva samples showed higher levels of stress hormones.

The researcher believes the brain needs at least ten days to recover after a long trip. He says airline workers told him their ability to remember got worse after working on planes for about four years. Other studies have shown that increased feelings of stress can cause a loss of cells in the part of the brain that controls memory.

Scientists say more tests are needed to study the effects of jet lag on the brain. They want to find out if too much jet lag could permanently affect memory.

47．According to the text, jet lag _____.

A. can cause difficulties in speaking  

B. can make people feel tired for a few weeks

C. can be only found in flight attendants

D. can be caused by flying over several time zones

48．It can be inferred from the text that ______.

A. the conclusion is refused by many scientists

B. scientists fear that this research is not done properly

C. every scientific conclusion needs the support from many tests

D. the women who were examined in the research were not healthy

49．From the result of the research we can see that _____.

A. the women who have longer rest at home perform better on the test.

B. the women who fly in short time have smaller right temporal lobes

C. the women who have longer flights fail the memory test

D. the women who rest more than 14 days produce more hormones

50．What is the subject discussed in the test?

A. The cause of jet lag.

B. A story of a group of flight attendants.

C. The importance of having enough rest after flights.

D. A research about the effects of jet lag on the brain.

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

What happens inside the skull of a soccer player who repeatedly heads a soccer ball? That question motivate a challenging new study of the brains of experienced players that has caused discussion and debate among soccer players, and some anxiety among those of us with soccer-playing children.
For the study, researchers at the Albert Einstein College of Medicine in New York selected 34 adults，men and women. All of the volunteers had played soccer since childhood and now competed year-round in adult soccer leagues. Each filled out a detailed questionnaire developed especially for this study to determine how many times they had headed a soccer ball in the previous year, as well as whether they had experienced any known concussions（脑震荡）in the past.
Then the players completed computerized tests of their memory and other learning skills and had their brains scanned, using a complicated new MRI technique which can find structural changes in the brain that can’t be seen during most scans.
According to the data they presented at a Radiological Society of North America meeting last month，the researchers found that the players who had headed the ball more than about 1,100 times in the previous 12 months showed significant loss of white matter in parts of their brains involved with memory，attention and the processing of visual information, compared with players who had headed the ball fewer times.
This pattern of white matter loss is “similar to those seen in traumatic（外伤的）brain injury” , like that after a serious concussion, the researchers reported，even though only one of these players was reported to have ever experienced a conc ussion.
The players who had headed the ball about 1,100 times or more in the past year were also generally worse at recalling lists of words read to them, forgetting or fumbling the words far more often than players who had headed the ball less.
【小题1】The passage is most probably a _________________.

What happens inside the skull of a soccer player who repeatedly heads a soccer ball? That question motivate a challenging new study of the brains of experienced players that has caused discussion and debate among soccer players, and some anxiety among those of us with soccer-playing children.

For the study, researchers at the Albert Einstein College of Medicine in New York selected 34 adults，men and women. All of the volunteers had played soccer since childhood and now competed year-round in adult soccer leagues. Each filled out a detailed questionnaire developed especially for this study to determine how many times they had headed a soccer ball in the previous year, as well as whether they had experienced any known concussions（脑震荡）in the past.

Then the players completed computerized tests of their memory and other learning skills and had their brains scanned, using a complicated new MRI technique which can find structural changes in the brain that can’t be seen during most scans.

According to the data they presented at a Radiological Society of North America meeting last month，the researchers found that the players who had headed the ball more than about 1,100 times in the previous 12 months showed significant loss of white matter in parts of their brains involved with memory，attention and the processing of visual information, compared with players who had headed the ball fewer times.

This pattern of white matter loss is “similar to those seen in traumatic（外伤的）brain injury” , like that after a serious concussion, the researchers reported，even though only one of these players was reported to have ever experienced a conc ussion.

The players who had headed the ball about 1,100 times or more in the past year were also generally worse at recalling lists of words read to them, forgetting or fumbling the words far more often than players who had headed the ball less.

1.The passage is most probably a _________________.

2.From the passage we can conclude that frequent heading may have  _________________.

3.What is likely to be the cause of memory loss?

4.The underlined word "fumbling" is closest in meaning to ________________.