The predictability of our death rates is something that has long puzzled social scientists. After all, there is no natural reason why 2,500 people should accidentally shoot themselves each year or why 7,000 should drown or 55,000 die in their cars. No one establishes a quota   for each type of death. It just happens that they follow a consistent pattern year after year. A few years ago a Canadian psychologist named Gerald Wilde became interested in this phenomenon. He noticed that mortality rates for violent and accidental deaths throughout the Western world have remained strangely static throughout the whole of the century, despite all the technological advances and increases in safety standards that have happened in that time. Wilde developed an interesting theory called "risk homeostasis". According to this theory, people naturally live with a certain level of risk. When something is made safer, people will get around the measure in some way to get back to the original level of danger. If, for instance, they are required to wear seat belts, they will feel safer and thus will drive a little faster and a little more recklessly, thereby statistically canceling out the benefits that the seat belt offers. Other studies have shown that where a crossing is made safer, the accident rate invariably falls there but rises elsewhere along the same stretch of road as if making up for the drop. It appears, then, that we have an inborn need for danger. In all events, it is becoming clearer and clearer to scientists that the factors influencing our lifespan are far more subtle and complex than had been previously thought. It now appears that if you wish to live a long life, it isn't simply a matter of paying attention to certain precautions such as eating the right foods, not smoking, and driving with care. You must also have the right attitude. Scientists at the Duke University Medical Center made a 15-year study of 500 persons personalities and found, somewhat to their surprise, that people with a suspicious or... By saying "statistically canceling out the benefits that the seat belt offers" (Para. 2), the author means   _  . A) wearing seat belts does not have any benefits from the statistic point of view B) deaths from wearing seat belts are the same as those from not wearing them C) deaths from other reasons counterbalance the benefits of wearing seat belts D) wearing seat belts does not necessarily reduce deaths from traffic accidents
C

If you see a person carelessly throw a cigarette to the ground, what are you likely to think? If you hate people throwing things on the ground, you might think, "That person shouldn't litter." If you are a smoker, you might think, "I would sure like a cigarette right now." Most likely, though, you are not thinking, "That unused cigarette butt could be used to make something amazing!" That is, unless you are a creative scientist. If you are, you may see potential--a possibility--where others simply see trash . That is just what has happened in South Korea. The spirit of invention can hit at the strangest times and in the most unusual places. In South Korea, it happened near a trash can. Kin Gil-Pyo is with  the Seoul National University. He says he saw people  throwing away cigarette butts, which got him thinking. He began wondering if something useful could be made from them. He and other researchers found a way to convert cigarette butts into materials required for high-performance batteries. Kim Gil-Pyo says they looked closely at used cigarette filters , the parts of cigarettes smokers put into their mouths. Filters are made of a material called "cellulose acetate ." Mr. Kim explains that cellulose acetate can be made into another material: carbon. The pieces of cellulose acetate, known as fibers, are changed through a one-step burning process. After this, they are turned into an energy storage material. But why use carbon? Carbon has many qualities that seem  to make it the perfect material. Carbon has a high surface area. It conducts electricity well. It also stays stable, unlikely to change, for a long time. And carbon does not cost a lot. All these qualities make it the most popular material for making super-capacitors . Super-capacitors are good at storing energy. They have high-power mass, or density . They require only a short time for recharging. And they have a long lifecycle. Super-capacitors are used in products such as laptop computers and cell phones. They are also used in industrial energy... The story tells the readers the truth that  _  . A) where there is a will, there is a way B) the most useless is usually the most useful C) ideas usually hit at the most unusual places D) one person's trash is another person's treasure
D

A hospital has been forced to ban Pokemon Go players from the site after a monster hub  was found in the A&E department. Royal Stoke University Hospital discovered that its casualty unit  is on the same spot as a Pokemon Go 'gym' ---- where players can train their newly caught Nintendo creatures. The University Hospitals of North Midlands Trust agreed last week that patients can play Pokemon Go on wards because walking around is healthy. But the Trust has been forced to post a warning on its website about public access to A&E. It said if Pokemon Go becomes a major annoyance it would ask Nintendo---- which decides on the locations of the virtual gyms according using GPS----to have it removed from the premises . Kevin Parker, associate chief nurse, said, "Members of the public who do not need to be at Royal Stoke should not attempt to enter A&E or any other part of the hospital building to play the game. The A&E department is incredibly busy this summer. We want the public to understand that anybody who visits the hospital solely to play the game will provide an unwanted distraction to the important work of the hospital. I'm also aware of various reports in the media of unsafe areas that the game has been played in." "Royal Stoke University Hospital is a safe area where gamers can enjoy Pokemon Go." Michelle Harris, the Trust's manager, said the game could still be played by those already in hospital. "We recognize that the Pokemon Go game encourages walking and exercise, which is something that the Trust is equally keen to promote," she said. There are a number of "walking routes" established throughout the Trust that can be used to combine walking and playing the game. "Walking just 30 minutes, five times a week, can help reduce the risk of preventable illnesses such as obesity, diabetes, and heart disease." There have been several warnings about the game since its UK release. Last week a group of teenagers in Wiltshire were left stranded almost 100ft underground after they got carried away searching for... The passage is mainly about  _  . A) the negative effects of Pokemon Go since its UK release B) the applications of Pokemon Go in hospitals since its UK release C) the popularity of Pokemon Go since its UK release D) the establishment of Pokemon Go virtual gyms since its UK release

A