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Fear and its companion pain are two of the most useful things that men and animals possess, if they are properly used. If fire did not hurt when it burnt, children would play it until their hands were burnt away. Similarly, if pain existed but fear did not, a child would burn itself again and again, because fear would not warn it to keep away from the fire that had burn it before. A really fearless soldier—and some do exist—is not a good soldier because he is soon killed; and a dead soldier is of no use to his army. Fear and pain are therefore two guards without which men and animals might soon die out. In our first sentence we suggested that fear ought to be properly used. If, for example, you never go out of your house because of the danger of being knocked down and killed in the street by a car, you are letting fear rule you too much. Even in your house you are not absolutely safe: an airplane may crash on your house, or ants may eat away some of the beams in your roof so that the latter falls on you, or you may get cancer! The important thing is not to let fear rule you, but instead to use fear as your servant and guide. Fear will warn you of dangers; then you have to decide what action to take. In many cases, you can take quick and successful action to avoid the danger. For example, you see a car coming straight towards you; fear warns you, you jump out of the way, and all is well. In some cases, however, you decide that there is nothing that you can do to avoid the danger. For example, you cannot prevent an airplane crashing onto your house. In this case, fear has given you its warning; you have examined it and decided on your course, of action, so fear of this particular danger is no longer of any use to you, and you have to try to overcome it. A really fearless soldier______.
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Many people believe the glare from snow causes snow blindness. Yet, dark glasses or not they find themselves suffering from headaches and watering eyes, and even snow-blindness, when exposed to several hours of "snow light". The United States Army has now determined that the glare from snow does not cause snow-blindness in troops in a snow-covered country. Rather, a man’’s eyes frequently find nothing to focus on in a broad expanse of a snow-covered area. So his gaze continually shifts and jumps back and forth over the entire landscape in search of something to look at. Finding nothing, hour after hour, the eyes never stop searching and the eyeballs become sore and the eye muscle aches. Nature balances this annoyance by producing more and more liquid which covers the eyeballs. The liquid covers the eyeballs in increasing quantity until vision blurs. And the result is total, even though temporary, snow-blindness. Experiments led the Army to a simple method of overcoming this problem. Scouts ahead of a main body of troops are trained to shake snow from evergreen bushes, creating a dotted line as they cross completely snow-covered landscape. Even the scouts themselves throw lightweight, dark-colored objects ahead on which they too can focus. The men following can then see something. Their gaze is arrested. Their eyes focus on a bush and having found something to see, stop searching through the snow-blanketed landscape. By focusing their attention on one object at a time, the man can cross the snow without becoming hopelessly snow-blind or lost. In this way the problem of crossing a solid white area is overcome. The first paragraph is mainly concerned with ______.
Besides information on the troubles with child-bearing, Planned Grandparenthood also offers guidance on ____________to children targeted by their parents to reproduce.
Questions 11 to 18 are based on the conversation you have just heard.
Few foods are more alluring than chocolate. "Chocolate is a drug of abuse in its own category," jokes Dr. Louis Aronne. "It’s ahnost as if people have chocolate receptors in their brains. " That may not be too far off the mark. In a recent book called "Breaking the Food Seduction," Dr. Neal Barnard contends that certain foods—including chocolate, cheese, red meat and practically anything combining sugar and fat—are just plain addictive. " It’s not that you lack willpower. These foods stimulate the release of chemicals in the brain’s pleasure center that keep you hooked. " Besides tapping the brain’s own "feel good" chemicals, Barnard says, some of these foods contain drug-like molecules (分子) of of their own. Cheese delivers casomorphins, the same compounds in a mother’s milk that help an infant bond during nursing, he says, but cheese is even more powerful, because it delivers casomorphins in an undiluted form. The result: "We’re bonding to our refrigerators. " Other scientists doubt these drug-like compounds have enough force to make the foods addictive. But no one denies that fat and sugar exert a strong appeal. The brain is designed to reward eating and other behaviors that promote survival. And throughout history, with food relatively hard to come by, what prmnoted survival better than calorie-dense foods packed with fat and sugar Besides, fat and sugar also calm the brain, lowering levels of stress hormones. "That’s why we call them comfort foods," says physiologist Mary Dallman. But comfort is different from addiction. In classic addiction, the brain grows less sensitive to a pleasurable substance, and the addict requires higher and higher doses to derive the same rewards. Can food cause that kind of change Perhaps. In a new study, Ann Kelley offered rats either plain water or a high-calorie chocolate drink. Over a two-week period, the animals drank more and more chocolate, but produced fewer brain opiates(镇静剂) in response. "You see the same thing in rats on morphine or heroin," she says. Admittedly, some foods can be hard to stop eating. But these foods are less habit-forming than alcohol—and most people can enjoy a drink without becoming alcoholic. The real problem today may be that we’re constantly surrounded with food—and can’t undo millions of years of evolution. According to Dr. Neal Barnard, which of the following food is addictive
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