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  3. If you want to increase your odds of having a long and lively lifetime, scientists say, work on getting an average of seven or e

If you want to increase your odds of having a long and lively lifetime, scientists say, work on getting an average of seven or e

admin2010-09-10  30
问题     If you want to increase your odds of having a long and lively lifetime, scientists say, work on getting an average of seven or eight hours of sleep a night. If you get only six hours or less, you stand a 70 percent chance of dying before your time.
    Scientists are finding that if you don’ t get enough sleep, you are putting yourself at increased risk of heart trouble, digestive disease, or a serious, even fatal (致命的) accident. When tired, your sight, hearing, and attention are slow to alert you to dangers--and once you are aware of them, your reactions are also slow.
    H. Craig Heller--a professor of biology at Stanford University--is one of a small army of scientists studying the reasons why many people can’ t sleep and wake refreshed, why the brain puts you to sleep, and why lack of sleep causes such powerful effects.
    Heller notes that most major accidents have occurred in the early morning, when workers probably were still sleepy from deficient (不足的) sleep. He includes the explosion at the nuclear power plant at Chernobyl in Ukraine, the release of poisonous gas at Bhopal, India and the nuclear accident at Three Mile Island in Pennsylvania.
    Scientists estimate that more than 100 million Americans have sleep troubles of some kind. Getting too little sleep heads the list. As many as one American in five gets fewer than six hours of sleep a night. Some people can get along on six hours, but most of us need between seven and eight--and children and young adults need up to 10 hours. As we age, it becomes more difficult to get enough sleep. At any age, however, we all can pile up a sleep deficit that eventual ly will force us to fall asleep-whether we’ re ready or not.
The phrase "such powerful effects" in Line 3 of Paragraph 3 refers to ______.
选项 A、the fact that many people cannot sleep and wake refreshed
B、the fact that the brain puts us to sleep when we are worn out
C、your sight, hearing, and attention are slow to alert you to dangers
D、increased risk of health problems or a serious, even deadly accident
答案D
解析 指代题。such一般用作回指。既然是powerful effects，那么就不会是指cannot sleep and wake refreshed和the brain puts us to sleep when we are worn out这类单一而且并不怎么powerful的事实。继续往前找，根据第二段第一句you are putting yourself at increased risk of heart trouble，digestive disease，or a serious，even fatal accident可知Heller所研究的还包括缺乏睡眠会造成上述这些恶果的原因，故答案为D。
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