题目内容
What Is Death？
People in the past did not question the difference between life and death. They could see that a person died when his heart stopped beating. People have learned, however, that the body does not die immediately when the heart stops beating. They discovered that we remain alive as long as our brain remains active. Today the difference between life and death is not as easy to see as in the past. Modern medical devices can keep the heart beating and the lungs breathing long after the brain stops. But is this life？
This question has caused much debate among citizens in the United States. Many of them want a law that says a person is dead when the brain dies. A person should be considered dead when brain waves stop even if machines can keep the body alive. Such a law would permit doctors to speed removal (切除) of undiseased (没病的) organs for transplant (移植) operations.
The brain is made of thousands of millions of nerve cells. These cells send and receive millions of chemical and electrical messages every day. In this way the brain controls the other body activities. Nerve-cell experts say it usually is easy to tell when the brain has died. They put small electrodes (电极) on a person's skull (头骨) to measure the electrical signals that pass in and out of the brain. These brain waves are recorded on a television screen or on paper. The waves move up and down every time the brain receives messages from the nerve cells. The brain is dead when the waves stop moving.
Although there are people who oppose the idea of a law on brain block for variouis reasons, the idea of brain wave activity as a test of death is slowly being accepted.
People in the past held that the difference between life and death______.
查看答案
搜索结果不匹配？点我反馈
更多问题
Stress Level Tied to Education Level
People with less education suffer fewer stressful days, according to a report in the current issue of the Journal of Health and Social Behavior.
However, the study also found that when less-educated people did suffer stress it was more severe and had a larger impact on their health.
From this researchers have concluded that the day-to-day factors that cause stress are not random. Where you are in society determines the kinds of problems that you have each day, and how well you will cope with them.
The research team interviewed a national sample of 1,031 adults daily for eight days about their stress level and health. People without a high school diploma reported stress on 30 percent of the study days, people with a high school degree reported stress 38 percent of the time, and people with college degrees reported stress 44 percent of the time.
"Less advantaged people are less healthy on a dally basis and are more likely to have downward turns in their health." lead researcher Dr. Joseph Grzywacz, of Wake Forest University Baptist Medical Center, said in a prepared statement. "The downward turns in health were connected with daily stressors, and the effect of daily stressors on their health is much more devastating for the less advantaged."
Grzywacz suggested follow-up research to determine why less-educated people report fewer days of stress when it is known their stress is more acute and chronic.
"If something happens every day, maybe it's not seen as a stressor." Grzywacz says. "Maybe it is just life."
stressor n. 紧张性刺激
devastating adj. 毁灭性的
follow-up n. (对病人的) 随访
Stress level is closely related to______.
Smoking
Since 1939, numerous studies have been conducted to determine whether smoking is a health hazard. The trend of the evidence has been consistent and indicates that there is a serious health risk. Research teams have conducted studies that show beyond all reasonable doubt that tobacco smoking is associated with a shortened life expectancy.
Cigarette smoking is believed by most research workers in this field to be an important factor in the development of cancer of the lungs and cancer of the throat and is believed to be related to cancer of some other organs of the body. Male cigarette smokers have a higher death rate from heart disease than non-smoking males. Female smokers are thought to be less affected because they do not breathe in the smoke so deeply.
Apart from statistics, it might be helpful to look at what tobacco does to the human body. Smoke is a mixture of gases, vaporized chemicals, minute particles of ash and other solids. There is also nicotine, which is powerful poison, and black tar. As smoke is breathed in, all those components from deposits on the membranes of the lungs. One point of concentration is where the air tube and bronchus divides. Most lung cancer begins at this point.
Filters and low tar tobacco are claimed to make smoking to some extent safer, but they can only slightly reduce, not eliminate the hazards.
It is easy to determine whether smoking is hazardous.
Which of the following tells us how caffeine affects sleep？
What does paragraph 3 mainly discuss？
微信支付 
支付宝支付