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Passage One

    Measuring a country's health by the average life expectancy of its citizens is a bit like judging the performance of the London Underground merely by the number of passengers it carries: It takes no account of how people find the experience as they go along. That is why the World Health Organization (WHO) has come up with a new measure of population health, called disability-adjusted life expectancy (DALE). Rather than estimating only how long a child can expect to live, Christopher Murray and his colleagues at the WHO have tried to calculate how much of the child's life will be spent in good health.

    To do this, they have conducted random surveys around the world to see how disabling such conditions as blindness or chest pain are considered to be. These "severity weightings", which vary surprisingly little from country to country, are combined with standard epidemiological measures of years of ill health due to particular ailments and deducted from total life expectancy to yield the DALE. Worldwide, the average healthy life expectancy of babies born in 1999 is 7.5 years less than their total life expectancy.

    Japan, Australia, France and Sweden all have DALES of more than 73 years. Indeed, the Japanese are not only the world's longest-lived people, with an average life expectancy of 81 years, but, according to this new measure, they are the heartiest, with only 6.5 years of their projected lifespan spent in ill health. Low rates of heart disease are credited as one explanation of Japan's strong showing. But the WHO warns that this may change as a consequence of fattier diets in recent years and greater cigarette consumption since the second world war.

    At the other extreme, the countries with the worst DALES are in sub-Saharan Africa. The healthy life expectancy for babies in Sierra Leone, Niger and Malawi is under 30 years. AIDS, along with malaria, tuberculosis and other infectious diseases, is ensuring that life remains nasty, brutish and short.

    Poverty is powerful ally of illness; but greater wealth does not necessarily buy better health. America is famously the world's biggest spender on health care, but with a DALE of 70 years, it still falls behind Japan, which forks out far less.

Dr. Murray admits that DALE is a rough-and-ready benchmark. Standard mortality statistics are hard to gather in some poor countries, let alone more sophisticated, culturally-sensitive assessments of illness severity. The WHO is busy working on both fronts to make DALE more reliable. If only the same could be said for the Underground.

    (425 words)

   1. The old measure of population health ________.( C )  

(a) is only useful in judging the performance of the London Underground

(b) can exactly estimate a child's life expectancy 

(c) cannot judge the citizens' performance in their experience

(d) can be applied in every country

2. DALE is ________.( D )

(a) the disabling condition such as blindness or chest pain

(b) another new measure of the WHO to estimate children's healthy conditions

(c) the severity weighting which varies little from country to country

(d) a measure to calculate how much of a child's life will be spent in good health

3. Which of the following statements is true?  ( B )

(a) Babies' life expectancy is shorter than their average healthy life expectancy.

(b) The countries with the worst DALEs are in sub-Saharan Africa.

(c) Japan, Austria, France and Sweden all have DALEs of more than 73 years.

(d) Japan has lagged behind because of fattier diets and greater cigarette consumption.

4.According to this passage, ________.( B )

(a) poverty is the most direct reason for the worse DALES in all countries

(b) the infectious disease are the main causes for the worst DALEs in some African countries

(c) the wealthier the country is, the healthier its people are

(d) advanced medical equipment and health care is the way to achieve the best DALES 

5. In Dr. Murray's view, DALE ________.( D )

(a) is very accurate in measuring population health

(b) is hard and impossible to be applied in some poor countries

(c) is not reliable enough and should be replaced in the future

(d) still faces challenges and difficulties, but it will be used widely

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Passage Two

    Perhaps you're the type of person who can decide to take a one-hour nap and actually wake up about an hour later. The reason both humans and animals are very good at estimating time for starting and stopping activities is the existence of a recently discovered clock in the brain, which is called the interval timing clock.

    The interval timing clock, which can be started and stopped like a stopwatch, gauges the passage of seconds, minutes, or hours and helps creatures time their movements, such as knowing when to start or stop doing some activity. The interval timing clock is located in a part of the brain known as the basal ganglia.

    When the interval clock was destroyed in rats, they could no longer time intervals for obtaining food. Researchers believe that, like the rat’s brain, the human brain has a similar interval timer that we can start and stop. However, deciding to nap for an hour is very different from the genetically set circadian clock that regulates waking and sleeping. The waking-sleeping clock was recently located in a group of cells in the suprachiasmatic nucleus.

    The suprachiasmatic nucleus is one of many groups of cells that make up the hypothalamus, which lies in the lower middle of the brain. The suprachiasmatic nucleus is a sophisticated biological clock that regulates a number of circadian rhythms, including the sleep-wake rhythm. Because this nucleus receives direct input from the eyes, the suprachiasmatic cells are highly responsive to changes in light.

    Researchers recently discovered the genes and movement proteins that make up suprachiasmatic nucleus's circadian clock. Since light regulates sleep-wake circadian rhythms, the absence of light should disrupt circadian rhythms in blind people and cause sleep problems. Researchers found that many blind people do report sleep problems. However, a small percentage of completely blind people reported no such problems because the pathway for transmitting light from their eyes directly to the suprachiasmatic nucleus was still in use. This pathway transmits only light and has nothing to do with vision.

    (336 words)

   6. The interval timing clock ________.( D )

(a) can estimate time accurately and never stops

(b) is a time-calculating function existing only in human's mind

(c) is known as the suprachiasmatic nucleus

(d) makes creatures good at starting and stopping at the right time

7. "Gauges" in the second paragraph probably means ________.( C )

(a) records

(b) checks

(c) measures

(d) helps

8. The suprachiasmatic nucleus is very sensitive to ________.( A )

(a) light

(b) sound

(c) heat

(d) cold

9. Light regulates sleep-wake circadian rhythms, ________.( C )

(a) and blind people have little sleep problems

(b) and completely blind people have no sleep problems

(c) but many blind people still report sleep problems

(d) and the absence of light cause no sleep problems

10. A good title for the passage is:  ________.( B )

(a) The Discovery of the Suprachiasmatic Nucleus

(b) Interval Timing and Sleep-Wake Clocks

(c) The Interval Timing Clock and the Blind

(d) Where is the Interval Timing Clock Located?

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Passage Three

    New measurements taken from sleeping people explain, at least in part, why dreams tend to have such bizarre but vivid storylines. The findings deal a blow to the Freudian interpretation of dreams but leave open the possibility that some useful personal meaning can be extracted from them. The main purpose of dreams, however, the authors of the new study believe, is to test whether the brain has had enough sleep and, if so, to wake it up.

    The new results show that in sleep, the frontal lobes of the brain are shut down. In the absence of activity in these lobes, which integrate other information and make sense of the outside world, the sleeping brain's images are driven by its emotional centers. The content of these dreams may be vivid and gripping but lacks coherence.

    The new results are consistent with the theory that memories are consolidated during sleep. From the pattern of activity that was recorded, "it seems that memories already in the system are being read out and filed in terms of their emotional salience, with is an extremely interesting idea," said Dr. J. Allan Hobson of Harvard Medical School.

    The new measurements were made by applying the technique known as PET scanning to sleeping subjects. The biologists focused on the two forms of sleep, known as slow-wave sleep and REM sleep. REM sleep, so named because of the rapid eyeball movements that occur then, takes place about four times during the night and is the phase from which the most vivid dreams are recalled.

    (257 words)

    11. According to this study, the purpose of the dreams is to ________.( A )

(a) test if the brain has had enough sleep

(b) show the dreamers bizarre but vivid storylines

(c) prove the correctness of the Freudian interpretation of dreams

(d) extract some useful personal meanings from the dreams

12. The researchers focus on REM sleep because ________.( D )

(a) it has rapid eyeball movements

(b) it takes place about four times during the night

(c) during REM sleep the content of the dreams is coherent

(d) it is the phase from which the most vivid dreams are recalled

13. The new results of the study ________.( C )

(a) show that in sleep the frontal lobes of the brain are active

(b) record the pattern of dream activity

(c) prove that memories are consolidated during sleep

(d) prove that dreams are based on and reflect daily facts

14. According to the passage, all of the following are true EXCEPT that ________.( A )

(a) the content of the dreams is not very consistent and seems very boring

(b) the technique, PET scanning, leads researchers to focus on two forms of sleep

(c) a man’s sleep can have two forms: slow-wave sleep and REM sleep

(d) in REM sleep, rapid eyeball movements occur

15. A good title for the passage is: ________.( A )

(a) Dream Aren’t Conflict Resolvers

(b) The Freudian Interpretation of Dreams

(c) Dr. J. Allan Hobson and His Researches

(d) Slow-Wave Sleep and REM Sleep    

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